Railway Interlocking System

Create massive train traffic on your own model railway!

Nov 28, 2019

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toys

remote control

Components and supplies

Generic Arduino sensor modules (Hall or IR)

5 mm LED: Green

Free URB unit

Resistor 221 ohm

Arduino Nano R3

Generic Motor-driver L298

Resistor 10k ohm

5 mm LED: Red

Apps and platforms

Arduino IDE

Project description

Code

LOCAL unit sketch

arduino

1// -------------------------------------------------- //
2// WWW.ARDUINORAILWAYCONTROL.COM                      //
3// local_urb.ino                                      //
4//  V.2.0  11/24/2019                                  //
5//                                                    //
6//  SMALL INTERLOCKING                                 //
7// For URB unit V.2.FINAL                             //
8// https://arduinorailwaycontrol.com/urb_unit.html    //
9//                                                    //
10// Author:  Steve Massikker                            //
11// --------------------------------------------------  //
12void(* resetFunc) (void) = 0;
13
14#include <Wire.h> 
15#include <Servo.h>
16
17//  SERVO
18#define JUNCTION_EN 4
19Servo J1;  // TURNOUT A
20Servo J2;  // TURNOUT  B
21
22// SIGNALS
23#define S_LA_RED 3 // SIGNAL LINE A
24#define S_LB_RED 2  // SIGNAL LINE B
25#define S_B3_RED 6 // SIGNAL BLOCK 3
26#define S_B3_GRN 5
27#define  S_OUT_RED 10 // SIGNAL OUT
28#define S_OUT_GRN 9
29#define S_B1_RED 17 // SIGNAL  BLOCK 1
30#define S_B1_GRN 16
31#define S_B2_RED 15 // SIGNAL BLOCK 2
32#define  S_B2_GRN 14
33
34
35// RELAY
36#define RELAY_LA 13 //  LINE A
37#define RELAY_LB  12 //  LINE B
38
39// Variables
40byte dataFromI2C;
41unsigned long millisJunctions,  timerStation;
42bool switch_A = true, 
43     switch_B = false,
44     flag_blink_AB  = false,
45     flag_change_junc = false;
46
47bool flag_interlocking = false,
48     flag_station_open = true;
49     
50bool open_block1 = true, 
51     open_block2  = true,
52     open_block3 = true;
53
54void setup() {
55
56  // Initializie  Hardware Serial & I2C
57  Serial.begin(9600);
58  Wire.begin(2); // Set address  #2
59  Wire.onReceive(receiveI2C);
60
61  // Initialize pins  
62  pinMode (JUNCTION_EN,  OUTPUT);
63  pinMode (RELAY_LA, OUTPUT);
64  pinMode (RELAY_LB, OUTPUT);  
65  pinMode (S_LA_RED, OUTPUT);
66  pinMode (S_LB_RED, OUTPUT);
67  pinMode (S_B3_GRN,  OUTPUT);
68  pinMode (S_B3_RED, OUTPUT);
69  pinMode (S_B1_RED, OUTPUT);
70  pinMode  (S_B1_GRN, OUTPUT);  
71  pinMode (S_B2_RED, OUTPUT);
72  pinMode (S_B2_GRN, OUTPUT);
73  pinMode (S_OUT_RED, OUTPUT);
74  pinMode (S_OUT_GRN, OUTPUT); 
75
76  // Initialize  Servos
77  J1.attach(7);
78  J2.attach(8);
79
80  // Set default
81  J1.write(180);  J2.write(0);
82  delay(900);
83  digitalWrite(JUNCTION_EN, LOW);
84  digitalWrite(S_LA_RED,  LOW); 
85  digitalWrite(S_LB_RED, HIGH);   
86  digitalWrite(S_B1_GRN, LOW);
87  digitalWrite(S_B1_RED, HIGH);
88  digitalWrite(S_B2_GRN, LOW);
89  digitalWrite(S_B2_RED,  HIGH);
90  digitalWrite(S_B3_GRN, LOW);
91  digitalWrite(S_B3_RED, HIGH);
92  digitalWrite(S_OUT_GRN, HIGH);    
93  digitalWrite(S_OUT_RED, LOW);
94  digitalWrite(RELAY_LA,  LOW); // Line A is ON 
95  digitalWrite(RELAY_LB, HIGH); // Line B is OFF
96}
97
98void  loop() {
99
100// ---- COMMAND PARSING
101  if (dataFromI2C != 0) {
102    
103    switch (dataFromI2C) {
104
105      // RESET
106      case 99: resetFunc();  break;
107
108      // SWITCH A
109      case 30: J1.write(0);
110           delay(50);
111           switch_A = false;
112           flag_change_junc = true;
113           digitalWrite(JUNCTION_EN,  HIGH);
114           Serial.println("SWITCH A Branch");
115           millisJunctions  = millis();
116           break;
117
118      case 31: J1.write(180);
119           delay(50);
120           switch_A = true;
121           flag_change_junc = true;         
122           digitalWrite(JUNCTION_EN, HIGH);
123           Serial.println("SWITCH  A Straight");         
124           millisJunctions = millis();
125           break;
126
127      // SWITCH B
128      case 32: J2.write(0);
129           delay(50);
130           switch_B  = false; 
131           flag_change_junc = true;             
132           digitalWrite(JUNCTION_EN,  HIGH);
133           Serial.println("SWITCH B Branch");
134           millisJunctions  = millis();
135           break;
136
137      case 33: J2.write(180);
138           delay(50);
139           switch_B = true; 
140           flag_change_junc = true;             
141           digitalWrite(JUNCTION_EN, HIGH);
142           Serial.println("SWITCH  B Straight");
143           millisJunctions= millis();
144           break;
145
146      // MODE
147      case 50: flag_interlocking = false;  
148           break;
149      case 51: flag_interlocking = true;  
150           break; 
151
152      //  BLOCKS STATE
153      case 101: open_block1 = false;
154           Serial.println("BLOCK  1");
155           break;
156      case 102: open_block2 = false;
157           open_block1  = true; 
158           Serial.println("BLOCK 2");           
159           break;
160      case 103: open_block3 = false;
161           open_block2 = true;
162           Serial.println("BLOCK  3");
163           break;
164      case 104: open_block3 = true;
165           flag_station_open  = false;
166           timerStation = millis();
167           Serial.println("OUT");
168           break;
169    }
170     
171    dataFromI2C = 0;
172  }
173
174// ----  SIGNALS
175  // BLOCK 1
176  if (flag_interlocking) {
177    if (open_block1) {
178      digitalWrite(S_B1_GRN, HIGH); 
179      digitalWrite(S_B1_RED, LOW);     
180    }
181    else {
182      digitalWrite(S_B1_GRN, LOW); 
183      digitalWrite(S_B1_RED,  HIGH); 
184    }
185  // BLOCK 2
186    if (open_block2) {
187      digitalWrite(S_B2_GRN,  HIGH); 
188      digitalWrite(S_B2_RED, LOW);     
189    }
190    else {
191      digitalWrite(S_B2_GRN,  LOW); 
192      digitalWrite(S_B2_RED, HIGH); 
193    }
194  // BLOCK 3
195    if  (open_block3) {
196      digitalWrite(S_B3_GRN, HIGH); 
197      digitalWrite(S_B3_RED,  LOW);     
198    }
199    else {
200      digitalWrite(S_B3_GRN, LOW); 
201      digitalWrite(S_B3_RED,  HIGH); 
202    }
203  }
204  else {
205    digitalWrite(S_B1_GRN, LOW);
206    digitalWrite(S_B1_RED,  HIGH);
207    digitalWrite(S_B2_GRN, LOW);
208    digitalWrite(S_B2_RED, HIGH);
209    digitalWrite(S_B3_GRN, LOW);
210    digitalWrite(S_B3_RED, HIGH);
211  }   
212
213  // OUT
214  if (flag_station_open) {
215    digitalWrite(S_OUT_GRN, HIGH);    
216    digitalWrite(S_OUT_RED, LOW);
217  }
218  else {
219    digitalWrite(S_OUT_GRN,  LOW);    
220    digitalWrite(S_OUT_RED, HIGH);
221  }
222
223// ---- RELAY
224  if (flag_change_junc) {
225
226  	if (switch_A && !switch_B) { // Line A
227      digitalWrite(S_LA_RED, LOW);
228      digitalWrite(S_LB_RED, HIGH); // RED     
229      digitalWrite(RELAY_LA, LOW);
230      digitalWrite(RELAY_LB, HIGH);  
231      flag_blink_AB = false;
232  	}
233  	else if (!switch_A && switch_B)  { // Line B
234      digitalWrite(S_LA_RED, HIGH); // RED
235      digitalWrite(S_LB_RED,  LOW);       
236      digitalWrite(RELAY_LA, HIGH); 
237      digitalWrite(RELAY_LB,  LOW); 
238      flag_blink_AB = false;     
239  	}
240  	else { // Undefined
241      digitalWrite(RELAY_LA, HIGH); 
242      digitalWrite(RELAY_LB, HIGH); 
243      flag_blink_AB = true;     
244  	}
245 
246    flag_change_junc = false;  
247  } 
248
249  if (millis() > (millisJunctions + 900)) digitalWrite(JUNCTION_EN,  LOW);
250  if (millis() > (timerStation + 15000)) flag_station_open = true; // Delay  15 sec.  
251
252  if (flag_blink_AB) {
253  	static bool tick_blink;
254    static  unsigned long blinkMillis;
255    if (millis() > (blinkMillis + 500)) { // 500 -  blinking optimal period
256      tick_blink = !tick_blink;
257      blinkMillis  = millis();
258    }
259    digitalWrite(S_LA_RED, tick_blink);
260    digitalWrite(S_LB_RED,  !tick_blink);
261  }
262
263}
264
265// ----------- FUNCTIONS ----------- //
266
267void  receiveI2C(int howMany) {
268  while (Wire.available() > 0) {
269    dataFromI2C  = Wire.read();
270  }
271}
272

// -------------------------------------------------- //
// WWW.ARDUINORAILWAYCONTROL.COM                      //
// local_urb.ino                                      //
//  V.2.0  11/24/2019                                  //
//                                                    //
//  SMALL INTERLOCKING                                 //
// For URB unit V.2.FINAL                             //
// https://arduinorailwaycontrol.com/urb_unit.html    //
//                                                    //
// Author:  Steve Massikker                            //
// --------------------------------------------------  //
void(* resetFunc) (void) = 0;

#include <Wire.h> 
#include <Servo.h>

//  SERVO
#define JUNCTION_EN 4
Servo J1;  // TURNOUT A
Servo J2;  // TURNOUT  B

// SIGNALS
#define S_LA_RED 3 // SIGNAL LINE A
#define S_LB_RED 2  // SIGNAL LINE B
#define S_B3_RED 6 // SIGNAL BLOCK 3
#define S_B3_GRN 5
#define  S_OUT_RED 10 // SIGNAL OUT
#define S_OUT_GRN 9
#define S_B1_RED 17 // SIGNAL  BLOCK 1
#define S_B1_GRN 16
#define S_B2_RED 15 // SIGNAL BLOCK 2
#define  S_B2_GRN 14


// RELAY
#define RELAY_LA 13 //  LINE A
#define RELAY_LB  12 //  LINE B

// Variables
byte dataFromI2C;
unsigned long millisJunctions,  timerStation;
bool switch_A = true, 
     switch_B = false,
     flag_blink_AB  = false,
     flag_change_junc = false;

bool flag_interlocking = false,
     flag_station_open = true;
     
bool open_block1 = true, 
     open_block2  = true,
     open_block3 = true;

void setup() {

  // Initializie  Hardware Serial & I2C
  Serial.begin(9600);
  Wire.begin(2); // Set address  #2
  Wire.onReceive(receiveI2C);

  // Initialize pins  
  pinMode (JUNCTION_EN,  OUTPUT);
  pinMode (RELAY_LA, OUTPUT);
  pinMode (RELAY_LB, OUTPUT);  
  pinMode (S_LA_RED, OUTPUT);
  pinMode (S_LB_RED, OUTPUT);
  pinMode (S_B3_GRN,  OUTPUT);
  pinMode (S_B3_RED, OUTPUT);
  pinMode (S_B1_RED, OUTPUT);
  pinMode  (S_B1_GRN, OUTPUT);  
  pinMode (S_B2_RED, OUTPUT);
  pinMode (S_B2_GRN, OUTPUT);
  pinMode (S_OUT_RED, OUTPUT);
  pinMode (S_OUT_GRN, OUTPUT); 

  // Initialize  Servos
  J1.attach(7);
  J2.attach(8);

  // Set default
  J1.write(180);  J2.write(0);
  delay(900);
  digitalWrite(JUNCTION_EN, LOW);
  digitalWrite(S_LA_RED,  LOW); 
  digitalWrite(S_LB_RED, HIGH);   
  digitalWrite(S_B1_GRN, LOW);
  digitalWrite(S_B1_RED, HIGH);
  digitalWrite(S_B2_GRN, LOW);
  digitalWrite(S_B2_RED,  HIGH);
  digitalWrite(S_B3_GRN, LOW);
  digitalWrite(S_B3_RED, HIGH);
  digitalWrite(S_OUT_GRN, HIGH);    
  digitalWrite(S_OUT_RED, LOW);
  digitalWrite(RELAY_LA,  LOW); // Line A is ON 
  digitalWrite(RELAY_LB, HIGH); // Line B is OFF
}

void  loop() {

// ---- COMMAND PARSING
  if (dataFromI2C != 0) {
    
    switch (dataFromI2C) {

      // RESET
      case 99: resetFunc();  break;

      // SWITCH A
      case 30: J1.write(0);
           delay(50);
           switch_A = false;
           flag_change_junc = true;
           digitalWrite(JUNCTION_EN,  HIGH);
           Serial.println("SWITCH A Branch");
           millisJunctions  = millis();
           break;

      case 31: J1.write(180);
           delay(50);
           switch_A = true;
           flag_change_junc = true;         
           digitalWrite(JUNCTION_EN, HIGH);
           Serial.println("SWITCH  A Straight");         
           millisJunctions = millis();
           break;

      // SWITCH B
      case 32: J2.write(0);
           delay(50);
           switch_B  = false; 
           flag_change_junc = true;             
           digitalWrite(JUNCTION_EN,  HIGH);
           Serial.println("SWITCH B Branch");
           millisJunctions  = millis();
           break;

      case 33: J2.write(180);
           delay(50);
           switch_B = true; 
           flag_change_junc = true;             
           digitalWrite(JUNCTION_EN, HIGH);
           Serial.println("SWITCH  B Straight");
           millisJunctions= millis();
           break;

      // MODE
      case 50: flag_interlocking = false;  
           break;
      case 51: flag_interlocking = true;  
           break; 

      //  BLOCKS STATE
      case 101: open_block1 = false;
           Serial.println("BLOCK  1");
           break;
      case 102: open_block2 = false;
           open_block1  = true; 
           Serial.println("BLOCK 2");           
           break;
      case 103: open_block3 = false;
           open_block2 = true;
           Serial.println("BLOCK  3");
           break;
      case 104: open_block3 = true;
           flag_station_open  = false;
           timerStation = millis();
           Serial.println("OUT");
           break;
    }
     
    dataFromI2C = 0;
  }

// ----  SIGNALS
  // BLOCK 1
  if (flag_interlocking) {
    if (open_block1) {
      digitalWrite(S_B1_GRN, HIGH); 
      digitalWrite(S_B1_RED, LOW);     
    }
    else {
      digitalWrite(S_B1_GRN, LOW); 
      digitalWrite(S_B1_RED,  HIGH); 
    }
  // BLOCK 2
    if (open_block2) {
      digitalWrite(S_B2_GRN,  HIGH); 
      digitalWrite(S_B2_RED, LOW);     
    }
    else {
      digitalWrite(S_B2_GRN,  LOW); 
      digitalWrite(S_B2_RED, HIGH); 
    }
  // BLOCK 3
    if  (open_block3) {
      digitalWrite(S_B3_GRN, HIGH); 
      digitalWrite(S_B3_RED,  LOW);     
    }
    else {
      digitalWrite(S_B3_GRN, LOW); 
      digitalWrite(S_B3_RED,  HIGH); 
    }
  }
  else {
    digitalWrite(S_B1_GRN, LOW);
    digitalWrite(S_B1_RED,  HIGH);
    digitalWrite(S_B2_GRN, LOW);
    digitalWrite(S_B2_RED, HIGH);
    digitalWrite(S_B3_GRN, LOW);
    digitalWrite(S_B3_RED, HIGH);
  }   

  // OUT
  if (flag_station_open) {
    digitalWrite(S_OUT_GRN, HIGH);    
    digitalWrite(S_OUT_RED, LOW);
  }
  else {
    digitalWrite(S_OUT_GRN,  LOW);    
    digitalWrite(S_OUT_RED, HIGH);
  }

// ---- RELAY
  if (flag_change_junc) {

  	if (switch_A && !switch_B) { // Line A
      digitalWrite(S_LA_RED, LOW);
      digitalWrite(S_LB_RED, HIGH); // RED     
      digitalWrite(RELAY_LA, LOW);
      digitalWrite(RELAY_LB, HIGH);  
      flag_blink_AB = false;
  	}
  	else if (!switch_A && switch_B)  { // Line B
      digitalWrite(S_LA_RED, HIGH); // RED
      digitalWrite(S_LB_RED,  LOW);       
      digitalWrite(RELAY_LA, HIGH); 
      digitalWrite(RELAY_LB,  LOW); 
      flag_blink_AB = false;     
  	}
  	else { // Undefined
      digitalWrite(RELAY_LA, HIGH); 
      digitalWrite(RELAY_LB, HIGH); 
      flag_blink_AB = true;     
  	}
 
    flag_change_junc = false;  
  } 

  if (millis() > (millisJunctions + 900)) digitalWrite(JUNCTION_EN,  LOW);
  if (millis() > (timerStation + 15000)) flag_station_open = true; // Delay  15 sec.  

  if (flag_blink_AB) {
  	static bool tick_blink;
    static  unsigned long blinkMillis;
    if (millis() > (blinkMillis + 500)) { // 500 -  blinking optimal period
      tick_blink = !tick_blink;
      blinkMillis  = millis();
    }
    digitalWrite(S_LA_RED, tick_blink);
    digitalWrite(S_LB_RED,  !tick_blink);
  }

}

// ----------- FUNCTIONS ----------- //

void  receiveI2C(int howMany) {
  while (Wire.available() > 0) {
    dataFromI2C  = Wire.read();
  }
}

COMM unit sketch

arduino

1// -------------------------------------------------- //
2// WWW.ARDUINORAILWAYCONTROL.COM                      //
3// comm_urb.ino                                       //
4//  V.2.0  11/24/2019                                  //
5//                                                    //
6//  SMALL INTERLOCKING                                 //
7// For URB unit V.2.FINAL                             //
8// 122Hz Thrust contol                                //
9//  https://arduinorailwaycontrol.com/urb_unit.html    //
10//                                                    //
11//  Author: Steve Massikker                            //
12// --------------------------------------------------  //
13void(* resetFunc) (void) = 0;
14
15#include <Wire.h>
16#include <SoftwareSerial.h>
17
18//  Bluetooth module
19SoftwareSerial Bluetooth(12, 13); // D12 - RX | D13 - TX
20
21//  PWM (SPEED)
22#define MD_1_ENA 10 // LINES A, B
23#define MD_1_ENB 9  // BLOCK  1
24#define MD_2_ENA 11 // BLOCK 3
25#define MD_2_ENB 3  // BLOCK 2
26// DIRECTION  DRIVER A 
27#define MD_1_IN1 4  
28#define MD_1_IN2 2
29// DIRECTION DRIVER B
30#define  MD_12_IN3_IN3_IN1 5 
31#define MD_12_IN4_IN4_IN2 6
32// SENSORS
33#define SNS_1  17
34#define SNS_2 14
35#define SNS_3 15
36#define SNS_4 7
37#define SNS_5 8
38#define  SNS_6 16
39#define SNS_7 A6
40
41// Variables
42int addressI2C;
43byte dataToI2C;
44bool  stringComplete = false;
45String inputString = "";
46
47  // 24 speed
48  byte  speedArrayA [] = {30,40,50,60,80,110,140,160,180,200,220,255};
49  byte speedTrainA  = 0;
50
51  // Interlocking
52  unsigned long timerBlock1, timerBlock2, timerBlock3,  timerStation;
53  byte speedBlock1, speedBlock2, speedBlock3; 
54  
55  // Dispather  AWS
56  bool flag_interlocking = false;  
57  bool flag_station_open = true;    
58
59  // Sensors
60  unsigned long timer_protected_sensor1, timer_protected_sensor3,
61                timer_protected_sensor5, timer_protected_sensor7;
62  bool protected_sensor1,  protected_sensor3, 
63       protected_sensor5, protected_sensor7;
64  bool sensor_block1_IN,  sensor_block2_IN, sensor_block3_IN, 
65       sensor_block1_OUT, sensor_block2_OUT,  sensor_block3_OUT, 
66       sensor_OUT;
67  bool latch_stop_block1, latch_stop_block2,  latch_stop_block3;
68  
69  // Latches     
70  bool open_block1 = true, open_block2  = true, open_block3 = true;
71
72  // TURNOUTS & SET DEFAULT POSITIONS
73  bool  switch_A = true, switch_B = false;
74      
75
76void setup() {
77
78  // Initializie  Serials & I2C
79  Serial.begin(9600);
80  Bluetooth.begin(9600);
81  inputString.reserve(4);
82  Wire.begin(); // Set as Master
83
84  // Initialize pins
85  pinMode (MD_1_ENA,  OUTPUT);
86  pinMode (MD_1_ENB, OUTPUT);
87  pinMode (MD_2_ENA, OUTPUT);
88  pinMode  (MD_2_ENB, OUTPUT);  
89  pinMode (MD_1_IN1, OUTPUT);
90  pinMode (MD_1_IN2, OUTPUT);
91  pinMode (MD_12_IN3_IN3_IN1, OUTPUT);
92  pinMode (MD_12_IN4_IN4_IN2, OUTPUT);  
93  pinMode (SNS_1, INPUT);
94  pinMode (SNS_2, INPUT);
95  pinMode (SNS_3,  INPUT);
96  pinMode (SNS_4, INPUT);
97  pinMode (SNS_5, INPUT);
98  pinMode (SNS_6,  INPUT);
99  pinMode (SNS_7, INPUT);  
100
101  // Set PWM frequency for D3, D9,  D10, D11
102  // Timer 1 divisor to 256 for PWM frequency of 122.55 Hz (9, 10)
103  TCCR1B = TCCR1B & B11111000 | B00000100;  
104  // Timer 2 divisor to 256 for  PWM frequency of 122.55 Hz (3, 11)
105  TCCR2B = TCCR2B & B11111000 | B00000100;  
106
107  // Set default direction to FORWARD (POLARITY)  NON Interlocking
108  digitalWrite(MD_1_IN1,  LOW);
109  digitalWrite(MD_1_IN2, HIGH); 
110  digitalWrite(MD_12_IN3_IN3_IN1, LOW);
111  digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
112 
113}
114
115void loop() {
116
117  // ----  START PARSING INCOMING APP COMMANDS
118  if (stringComplete) {
119    //  RESET 
120    if (inputString =="999z") {
121      dataToI2C = 99;
122      addressI2C  = 2;      
123      sendDataViaI2C();
124      resetFunc();
125    }
126
127    //  FUNCTIONS 
128    if (inputString.charAt(0) =='a') {
129        // Speed   
130      if (inputString.charAt(1) =='0') {
131        if (inputString.charAt(2) =='0')  speedTrainA = 0;
132        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[0];
133        if (inputString.charAt(2) =='4') speedTrainA = speedArrayA[1];
134        if  (inputString.charAt(2) =='6') speedTrainA = speedArrayA[2];
135        if (inputString.charAt(2)  =='8') speedTrainA = speedArrayA[3]; 
136      } 
137      if (inputString.charAt(1)  =='1') {
138        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[4];
139        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[5];
140        if  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[6];
141        if (inputString.charAt(2)  =='6') speedTrainA = speedArrayA[7];
142        if (inputString.charAt(2) =='8')  speedTrainA = speedArrayA[8];
143      }
144      if (inputString.charAt(1) =='2')  {
145        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[9];
146        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[10];
147        if  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[11];         
148      }
149
150      // Direction and Stop
151      if (inputString.charAt(1) =='d') {
152        if  (inputString.charAt(2) =='f') { // (f) Forward
153          digitalWrite(MD_1_IN1,  LOW);
154          digitalWrite(MD_1_IN2, HIGH); 
155          digitalWrite(MD_12_IN3_IN3_IN1,  LOW);
156          digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
157        }
158        if  (inputString.charAt(2) =='b') { // (b) Backward - Interlocking
159          digitalWrite(MD_1_IN1,  HIGH);
160          digitalWrite(MD_1_IN2, LOW); 
161          digitalWrite(MD_12_IN3_IN3_IN1,  HIGH); 
162          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
163        }
164        if  (inputString.charAt(2) =='s') { // (s) Stop button
165          speedTrainA = 0;
166        } 
167
168        analogWrite(MD_1_ENA, speedTrainA); // Throttle Driver  A
169        
170        if (!flag_interlocking) {
171          analogWrite(MD_1_ENB,  speedTrainA);
172          analogWrite(MD_2_ENB, speedTrainA);
173          if (flag_station_open)  analogWrite(MD_2_ENA, speedTrainA); 
174          else analogWrite(MD_2_ENA,0);  
175        }    
176      }
177    }  
178
179    if (inputString.charAt(0) =='j')  {
180      // Switch A
181      if (inputString.charAt(1) =='a') { 
182        if  (inputString.charAt(2) =='0') { // Branch direction
183          switch_A = false;
184          Bluetooth.print("a0z"); // Feedback to App
185          Serial.print("a0z");
186          addressI2C = 2; dataToI2C = 30; sendDataViaI2C();
187        }
188        if  (inputString.charAt(2) =='1') { // Throw direction
189          switch_A = true;
190          Bluetooth.print("a1z"); // Feedback to App
191          Serial.print("a1z");      
192          addressI2C = 2; dataToI2C = 31; sendDataViaI2C();
193        }  
194      }
195
196      // Switch B
197      if (inputString.charAt(1) =='b') {  
198        if (inputString.charAt(2) =='0') {
199          switch_B = false;
200          Bluetooth.print("b0z"); 
201          Serial.print("b0z");
202          addressI2C  = 2; dataToI2C = 32; sendDataViaI2C();
203        }
204        if (inputString.charAt(2)  =='1') {
205          switch_B = true;
206          Bluetooth.print("b1z");
207          Serial.print("b1z");      
208          addressI2C = 2; dataToI2C =  33; sendDataViaI2C();
209        } 
210      }
211    }
212    
213    // AUTOMATE  ON | OFF
214    if (inputString.charAt(0) =='f') {
215      if (inputString.charAt(1)  =='a') {
216
217        if (inputString.charAt(2) =='0') {
218          flag_interlocking  = false;
219          speedBlock1 = 0; speedBlock2 = 0; speedBlock3 = 0;
220          addressI2C  = 2; dataToI2C = 50; sendDataViaI2C(); // AUTOMATE OFF
221        }
222        if  (inputString.charAt(2) =='1') {
223          flag_interlocking = true;
224          speedBlock1  = 180; speedBlock2 = 140; speedBlock3 = 160;
225          digitalWrite(MD_1_IN1,  HIGH);
226          digitalWrite(MD_1_IN2, LOW); 
227          digitalWrite(MD_12_IN3_IN3_IN1,  HIGH); 
228          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
229          protected_sensor1  = false; protected_sensor3 = false;
230          protected_sensor5 = false; protected_sensor7  = false;
231          latch_stop_block1 = false; latch_stop_block2 = false; latch_stop_block3  = false;
232          open_block1 = true; open_block2 = true; open_block3 = true;          
233          addressI2C = 2; dataToI2C = 51; sendDataViaI2C(); // AUTOMATE  ON
234        }
235
236        analogWrite(MD_1_ENB, speedBlock1);
237        analogWrite(MD_2_ENB,  speedBlock2);
238        analogWrite(MD_2_ENA, speedBlock3); 
239      }  
240    }
241
242    dataToI2C = 0;
243    inputString = "";
244    stringComplete = false;
245  }
246
247  // ----  MAIN BLOCK
248  if (flag_interlocking) {
249
250    // CHECK  SENSORS STATES
251
252    if (digitalRead(SNS_1) == LOW) { // BLOCK 1 | HALL
253      sensor_block1_IN = true;
254      open_block1 = false;
255      //Serial.println("SENSOR  1");
256    }
257    else sensor_block1_IN = false; 
258    if (digitalRead(SNS_2)  == LOW) { // HALL
259      sensor_block1_OUT = true;
260      latch_stop_block1  = true;
261      //Serial.println("SENSOR 2");    
262    }
263    else sensor_block1_OUT  = false;
264  
265    if (digitalRead(SNS_3) == HIGH) { // BLOCK 2 | IR
266      sensor_block2_IN  = true;
267      open_block2 = false;
268      //Serial.println("SENSOR 3");    
269    }
270    else sensor_block2_IN = false; 
271    if (digitalRead(SNS_4) == LOW)  { // HALL
272      sensor_block2_OUT = true;
273      latch_stop_block2 = true;
274      //Serial.println("SENSOR 4");    
275    }
276    else sensor_block2_OUT  = false;  
277    
278    if (digitalRead(SNS_5) == HIGH) { // BLOCK 3 | IR
279      sensor_block3_IN = true;
280      open_block3 = false;
281      //Serial.println("SENSOR  5");    
282    }
283    else sensor_block3_IN = false;
284    if (digitalRead(SNS_6)  == LOW) { // HALL
285      sensor_block3_OUT = true;  
286      latch_stop_block3  = true;
287      //Serial.println("SENSOR 6");    
288    }
289    else sensor_block3_OUT  = false;  
290    
291    // OUT
292    if (analogRead(SNS_7) > 550) { // ANALOGUE  HALL
293      sensor_OUT = true;
294      //Serial.println("SENSOR 7");
295    }      
296    else sensor_OUT = false;   
297  
298    // RESET BLOCK LATCHES
299    if (sensor_block2_IN) open_block1 = true; 
300    if (sensor_block3_IN) open_block2  = true;
301    if (sensor_OUT) open_block3 = true;
302
303    // RESET AUTOSTOP  LATCHES
304    if (sensor_block2_IN) latch_stop_block1 = false;
305    if (sensor_block3_IN)  latch_stop_block2 = false;        
306    if (sensor_OUT) latch_stop_block3 = false;
307    
308    // ----  SIGNALS
309    // SIGNAL 1
310    if (sensor_block1_IN && !protected_sensor1)  {
311      timer_protected_sensor1 = millis();
312      protected_sensor1 = true;  
313      addressI2C = 2; dataToI2C = 101; sendDataViaI2C();
314    }  
315    //  SIGNAL 2
316    if (sensor_block2_IN && !protected_sensor3) {
317      timer_protected_sensor3  = millis();
318      protected_sensor3 = true;      
319      addressI2C = 2; dataToI2C  = 102; sendDataViaI2C();
320    }    
321    // SIGNAL 3
322    if (sensor_block3_IN  && !protected_sensor5) {
323      timer_protected_sensor5 = millis();
324      protected_sensor5  = true;       
325      addressI2C = 2; dataToI2C = 103; sendDataViaI2C();
326    }  
327    // SIGNAL 4 
328    if (sensor_OUT && !protected_sensor7) {
329      timer_protected_sensor7  = millis();
330      timerStation = millis();
331      protected_sensor7 = true;  
332      flag_station_open = false;      
333      addressI2C = 2; dataToI2C =  104; sendDataViaI2C();
334    } 
335
336  // AUTOSTOP
337    // BLOCK 1
338    if  (!open_block2) {
339      if (latch_stop_block1) {
340        if (millis() > (timerBlock1  + 100)) {
341          timerBlock1 = millis();
342          if (speedBlock1 > 40)  speedBlock1 = speedBlock1 - 25;
343          else speedBlock1 = 0;
344        }
345      }  
346    }
347    else speedBlock1 = 180;
348
349    // BLOCK 2
350    if  (!open_block3) {
351      if (latch_stop_block2) {
352        if (millis() > (timerBlock2  + 100)) {
353          timerBlock2 = millis();
354          if (speedBlock2 > 60)  speedBlock2 = speedBlock2 - 30;
355          else speedBlock2 = 0;
356        }
357      }  
358    }
359    else speedBlock2 = 140;
360
361    // BLOCK 3
362    if  (!flag_station_open) {
363      if (latch_stop_block3) {
364        if (millis()  > (timerBlock3 + 100)) {
365          timerBlock3 = millis();
366          if (speedBlock3  > 40) speedBlock3 = speedBlock3 - 18;
367          else speedBlock3 = 0;
368        }
369      } 
370    }
371    else speedBlock3 = 160;
372    
373    analogWrite(MD_1_ENB,  speedBlock1);
374    analogWrite(MD_2_ENB, speedBlock2);
375    analogWrite(MD_2_ENA,  speedBlock3);     
376  }
377
378  // ----  TIMERS
379  if (millis() > (timer_protected_sensor1  + 1000)) protected_sensor1 = false;
380  if (millis() > (timer_protected_sensor3  + 1500)) protected_sensor3 = false;
381  if (millis() > (timer_protected_sensor5  + 1500)) protected_sensor5 = false;
382  if (millis() > (timer_protected_sensor7  + 1000)) protected_sensor7 = false;
383  if (millis() > (timerStation + 15000))  flag_station_open = true; // Delay 15 sec.
384
385  bluetoothEvent();
386
387}  
388
389//  ----------- FUNCTIONS ----------- //
390void serialEvent() {
391  if (Serial.available())  {
392    char inChar = (char)Serial.read();
393    inputString += inChar;
394    if  (inChar == 'z') {
395      stringComplete = true;
396    }
397  }
398}
399
400void  bluetoothEvent() {
401  if (Bluetooth.available()) {
402    char inChar = (char)Bluetooth.read();
403    inputString += inChar;
404    if (inChar == 'z') {
405      //Serial.println(inputString);  // Command from App
406      stringComplete = true;
407    }
408  }
409}
410
411void  sendDataViaI2C() {
412  Wire.beginTransmission(addressI2C);
413  Wire.write(dataToI2C);
414  Wire.endTransmission();
415}

// -------------------------------------------------- //
// WWW.ARDUINORAILWAYCONTROL.COM                      //
// comm_urb.ino                                       //
//  V.2.0  11/24/2019                                  //
//                                                    //
//  SMALL INTERLOCKING                                 //
// For URB unit V.2.FINAL                             //
// 122Hz Thrust contol                                //
//  https://arduinorailwaycontrol.com/urb_unit.html    //
//                                                    //
//  Author: Steve Massikker                            //
// --------------------------------------------------  //
void(* resetFunc) (void) = 0;

#include <Wire.h>
#include <SoftwareSerial.h>

//  Bluetooth module
SoftwareSerial Bluetooth(12, 13); // D12 - RX | D13 - TX

//  PWM (SPEED)
#define MD_1_ENA 10 // LINES A, B
#define MD_1_ENB 9  // BLOCK  1
#define MD_2_ENA 11 // BLOCK 3
#define MD_2_ENB 3  // BLOCK 2
// DIRECTION  DRIVER A 
#define MD_1_IN1 4  
#define MD_1_IN2 2
// DIRECTION DRIVER B
#define  MD_12_IN3_IN3_IN1 5 
#define MD_12_IN4_IN4_IN2 6
// SENSORS
#define SNS_1  17
#define SNS_2 14
#define SNS_3 15
#define SNS_4 7
#define SNS_5 8
#define  SNS_6 16
#define SNS_7 A6

// Variables
int addressI2C;
byte dataToI2C;
bool  stringComplete = false;
String inputString = "";

  // 24 speed
  byte  speedArrayA [] = {30,40,50,60,80,110,140,160,180,200,220,255};
  byte speedTrainA  = 0;

  // Interlocking
  unsigned long timerBlock1, timerBlock2, timerBlock3,  timerStation;
  byte speedBlock1, speedBlock2, speedBlock3; 
  
  // Dispather  AWS
  bool flag_interlocking = false;  
  bool flag_station_open = true;    

  // Sensors
  unsigned long timer_protected_sensor1, timer_protected_sensor3,
                timer_protected_sensor5, timer_protected_sensor7;
  bool protected_sensor1,  protected_sensor3, 
       protected_sensor5, protected_sensor7;
  bool sensor_block1_IN,  sensor_block2_IN, sensor_block3_IN, 
       sensor_block1_OUT, sensor_block2_OUT,  sensor_block3_OUT, 
       sensor_OUT;
  bool latch_stop_block1, latch_stop_block2,  latch_stop_block3;
  
  // Latches     
  bool open_block1 = true, open_block2  = true, open_block3 = true;

  // TURNOUTS & SET DEFAULT POSITIONS
  bool  switch_A = true, switch_B = false;
      

void setup() {

  // Initializie  Serials & I2C
  Serial.begin(9600);
  Bluetooth.begin(9600);
  inputString.reserve(4);
  Wire.begin(); // Set as Master

  // Initialize pins
  pinMode (MD_1_ENA,  OUTPUT);
  pinMode (MD_1_ENB, OUTPUT);
  pinMode (MD_2_ENA, OUTPUT);
  pinMode  (MD_2_ENB, OUTPUT);  
  pinMode (MD_1_IN1, OUTPUT);
  pinMode (MD_1_IN2, OUTPUT);
  pinMode (MD_12_IN3_IN3_IN1, OUTPUT);
  pinMode (MD_12_IN4_IN4_IN2, OUTPUT);  
  pinMode (SNS_1, INPUT);
  pinMode (SNS_2, INPUT);
  pinMode (SNS_3,  INPUT);
  pinMode (SNS_4, INPUT);
  pinMode (SNS_5, INPUT);
  pinMode (SNS_6,  INPUT);
  pinMode (SNS_7, INPUT);  

  // Set PWM frequency for D3, D9,  D10, D11
  // Timer 1 divisor to 256 for PWM frequency of 122.55 Hz (9, 10)
  TCCR1B = TCCR1B & B11111000 | B00000100;  
  // Timer 2 divisor to 256 for  PWM frequency of 122.55 Hz (3, 11)
  TCCR2B = TCCR2B & B11111000 | B00000100;  

  // Set default direction to FORWARD (POLARITY)  NON Interlocking
  digitalWrite(MD_1_IN1,  LOW);
  digitalWrite(MD_1_IN2, HIGH); 
  digitalWrite(MD_12_IN3_IN3_IN1, LOW);
  digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
 
}

void loop() {

  // ----  START PARSING INCOMING APP COMMANDS
  if (stringComplete) {
    //  RESET 
    if (inputString =="999z") {
      dataToI2C = 99;
      addressI2C  = 2;      
      sendDataViaI2C();
      resetFunc();
    }

    //  FUNCTIONS 
    if (inputString.charAt(0) =='a') {
        // Speed   
      if (inputString.charAt(1) =='0') {
        if (inputString.charAt(2) =='0')  speedTrainA = 0;
        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[0];
        if (inputString.charAt(2) =='4') speedTrainA = speedArrayA[1];
        if  (inputString.charAt(2) =='6') speedTrainA = speedArrayA[2];
        if (inputString.charAt(2)  =='8') speedTrainA = speedArrayA[3]; 
      } 
      if (inputString.charAt(1)  =='1') {
        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[4];
        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[5];
        if  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[6];
        if (inputString.charAt(2)  =='6') speedTrainA = speedArrayA[7];
        if (inputString.charAt(2) =='8')  speedTrainA = speedArrayA[8];
      }
      if (inputString.charAt(1) =='2')  {
        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[9];
        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[10];
        if  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[11];         
      }

      // Direction and Stop
      if (inputString.charAt(1) =='d') {
        if  (inputString.charAt(2) =='f') { // (f) Forward
          digitalWrite(MD_1_IN1,  LOW);
          digitalWrite(MD_1_IN2, HIGH); 
          digitalWrite(MD_12_IN3_IN3_IN1,  LOW);
          digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
        }
        if  (inputString.charAt(2) =='b') { // (b) Backward - Interlocking
          digitalWrite(MD_1_IN1,  HIGH);
          digitalWrite(MD_1_IN2, LOW); 
          digitalWrite(MD_12_IN3_IN3_IN1,  HIGH); 
          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
        }
        if  (inputString.charAt(2) =='s') { // (s) Stop button
          speedTrainA = 0;
        } 

        analogWrite(MD_1_ENA, speedTrainA); // Throttle Driver  A
        
        if (!flag_interlocking) {
          analogWrite(MD_1_ENB,  speedTrainA);
          analogWrite(MD_2_ENB, speedTrainA);
          if (flag_station_open)  analogWrite(MD_2_ENA, speedTrainA); 
          else analogWrite(MD_2_ENA,0);  
        }    
      }
    }  

    if (inputString.charAt(0) =='j')  {
      // Switch A
      if (inputString.charAt(1) =='a') { 
        if  (inputString.charAt(2) =='0') { // Branch direction
          switch_A = false;
          Bluetooth.print("a0z"); // Feedback to App
          Serial.print("a0z");
          addressI2C = 2; dataToI2C = 30; sendDataViaI2C();
        }
        if  (inputString.charAt(2) =='1') { // Throw direction
          switch_A = true;
          Bluetooth.print("a1z"); // Feedback to App
          Serial.print("a1z");      
          addressI2C = 2; dataToI2C = 31; sendDataViaI2C();
        }  
      }

      // Switch B
      if (inputString.charAt(1) =='b') {  
        if (inputString.charAt(2) =='0') {
          switch_B = false;
          Bluetooth.print("b0z"); 
          Serial.print("b0z");
          addressI2C  = 2; dataToI2C = 32; sendDataViaI2C();
        }
        if (inputString.charAt(2)  =='1') {
          switch_B = true;
          Bluetooth.print("b1z");
          Serial.print("b1z");      
          addressI2C = 2; dataToI2C =  33; sendDataViaI2C();
        } 
      }
    }
    
    // AUTOMATE  ON | OFF
    if (inputString.charAt(0) =='f') {
      if (inputString.charAt(1)  =='a') {

        if (inputString.charAt(2) =='0') {
          flag_interlocking  = false;
          speedBlock1 = 0; speedBlock2 = 0; speedBlock3 = 0;
          addressI2C  = 2; dataToI2C = 50; sendDataViaI2C(); // AUTOMATE OFF
        }
        if  (inputString.charAt(2) =='1') {
          flag_interlocking = true;
          speedBlock1  = 180; speedBlock2 = 140; speedBlock3 = 160;
          digitalWrite(MD_1_IN1,  HIGH);
          digitalWrite(MD_1_IN2, LOW); 
          digitalWrite(MD_12_IN3_IN3_IN1,  HIGH); 
          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
          protected_sensor1  = false; protected_sensor3 = false;
          protected_sensor5 = false; protected_sensor7  = false;
          latch_stop_block1 = false; latch_stop_block2 = false; latch_stop_block3  = false;
          open_block1 = true; open_block2 = true; open_block3 = true;          
          addressI2C = 2; dataToI2C = 51; sendDataViaI2C(); // AUTOMATE  ON
        }

        analogWrite(MD_1_ENB, speedBlock1);
        analogWrite(MD_2_ENB,  speedBlock2);
        analogWrite(MD_2_ENA, speedBlock3); 
      }  
    }

    dataToI2C = 0;
    inputString = "";
    stringComplete = false;
  }

  // ----  MAIN BLOCK
  if (flag_interlocking) {

    // CHECK  SENSORS STATES

    if (digitalRead(SNS_1) == LOW) { // BLOCK 1 | HALL
      sensor_block1_IN = true;
      open_block1 = false;
      //Serial.println("SENSOR  1");
    }
    else sensor_block1_IN = false; 
    if (digitalRead(SNS_2)  == LOW) { // HALL
      sensor_block1_OUT = true;
      latch_stop_block1  = true;
      //Serial.println("SENSOR 2");    
    }
    else sensor_block1_OUT  = false;
  
    if (digitalRead(SNS_3) == HIGH) { // BLOCK 2 | IR
      sensor_block2_IN  = true;
      open_block2 = false;
      //Serial.println("SENSOR 3");    
    }
    else sensor_block2_IN = false; 
    if (digitalRead(SNS_4) == LOW)  { // HALL
      sensor_block2_OUT = true;
      latch_stop_block2 = true;
      //Serial.println("SENSOR 4");    
    }
    else sensor_block2_OUT  = false;  
    
    if (digitalRead(SNS_5) == HIGH) { // BLOCK 3 | IR
      sensor_block3_IN = true;
      open_block3 = false;
      //Serial.println("SENSOR  5");    
    }
    else sensor_block3_IN = false;
    if (digitalRead(SNS_6)  == LOW) { // HALL
      sensor_block3_OUT = true;  
      latch_stop_block3  = true;
      //Serial.println("SENSOR 6");    
    }
    else sensor_block3_OUT  = false;  
    
    // OUT
    if (analogRead(SNS_7) > 550) { // ANALOGUE  HALL
      sensor_OUT = true;
      //Serial.println("SENSOR 7");
    }      
    else sensor_OUT = false;   
  
    // RESET BLOCK LATCHES
    if (sensor_block2_IN) open_block1 = true; 
    if (sensor_block3_IN) open_block2  = true;
    if (sensor_OUT) open_block3 = true;

    // RESET AUTOSTOP  LATCHES
    if (sensor_block2_IN) latch_stop_block1 = false;
    if (sensor_block3_IN)  latch_stop_block2 = false;        
    if (sensor_OUT) latch_stop_block3 = false;
    
    // ----  SIGNALS
    // SIGNAL 1
    if (sensor_block1_IN && !protected_sensor1)  {
      timer_protected_sensor1 = millis();
      protected_sensor1 = true;  
      addressI2C = 2; dataToI2C = 101; sendDataViaI2C();
    }  
    //  SIGNAL 2
    if (sensor_block2_IN && !protected_sensor3) {
      timer_protected_sensor3  = millis();
      protected_sensor3 = true;      
      addressI2C = 2; dataToI2C  = 102; sendDataViaI2C();
    }    
    // SIGNAL 3
    if (sensor_block3_IN  && !protected_sensor5) {
      timer_protected_sensor5 = millis();
      protected_sensor5  = true;       
      addressI2C = 2; dataToI2C = 103; sendDataViaI2C();
    }  
    // SIGNAL 4 
    if (sensor_OUT && !protected_sensor7) {
      timer_protected_sensor7  = millis();
      timerStation = millis();
      protected_sensor7 = true;  
      flag_station_open = false;      
      addressI2C = 2; dataToI2C =  104; sendDataViaI2C();
    } 

  // AUTOSTOP
    // BLOCK 1
    if  (!open_block2) {
      if (latch_stop_block1) {
        if (millis() > (timerBlock1  + 100)) {
          timerBlock1 = millis();
          if (speedBlock1 > 40)  speedBlock1 = speedBlock1 - 25;
          else speedBlock1 = 0;
        }
      }  
    }
    else speedBlock1 = 180;

    // BLOCK 2
    if  (!open_block3) {
      if (latch_stop_block2) {
        if (millis() > (timerBlock2  + 100)) {
          timerBlock2 = millis();
          if (speedBlock2 > 60)  speedBlock2 = speedBlock2 - 30;
          else speedBlock2 = 0;
        }
      }  
    }
    else speedBlock2 = 140;

    // BLOCK 3
    if  (!flag_station_open) {
      if (latch_stop_block3) {
        if (millis()  > (timerBlock3 + 100)) {
          timerBlock3 = millis();
          if (speedBlock3  > 40) speedBlock3 = speedBlock3 - 18;
          else speedBlock3 = 0;
        }
      } 
    }
    else speedBlock3 = 160;
    
    analogWrite(MD_1_ENB,  speedBlock1);
    analogWrite(MD_2_ENB, speedBlock2);
    analogWrite(MD_2_ENA,  speedBlock3);     
  }

  // ----  TIMERS
  if (millis() > (timer_protected_sensor1  + 1000)) protected_sensor1 = false;
  if (millis() > (timer_protected_sensor3  + 1500)) protected_sensor3 = false;
  if (millis() > (timer_protected_sensor5  + 1500)) protected_sensor5 = false;
  if (millis() > (timer_protected_sensor7  + 1000)) protected_sensor7 = false;
  if (millis() > (timerStation + 15000))  flag_station_open = true; // Delay 15 sec.

  bluetoothEvent();

}  

//  ----------- FUNCTIONS ----------- //
void serialEvent() {
  if (Serial.available())  {
    char inChar = (char)Serial.read();
    inputString += inChar;
    if  (inChar == 'z') {
      stringComplete = true;
    }
  }
}

void  bluetoothEvent() {
  if (Bluetooth.available()) {
    char inChar = (char)Bluetooth.read();
    inputString += inChar;
    if (inChar == 'z') {
      //Serial.println(inputString);  // Command from App
      stringComplete = true;
    }
  }
}

void  sendDataViaI2C() {
  Wire.beginTransmission(addressI2C);
  Wire.write(dataToI2C);
  Wire.endTransmission();
}

COMM unit sketch

arduino

1// -------------------------------------------------- //
2// WWW.ARDUINORAILWAYCONTROL.COM
3                      //
4// comm_urb.ino                                       //
5//
6  V.2.0  11/24/2019                                  //
7//                                                    //
8//
9  SMALL INTERLOCKING                                 //
10// For URB unit V.2.FINAL
11                             //
12// 122Hz Thrust contol                                //
13//
14  https://arduinorailwaycontrol.com/urb_unit.html    //
15//                                                    //
16//
17  Author: Steve Massikker                            //
18// --------------------------------------------------
19  //
20void(* resetFunc) (void) = 0;
21
22#include <Wire.h>
23#include <SoftwareSerial.h>
24
25//
26  Bluetooth module
27SoftwareSerial Bluetooth(12, 13); // D12 - RX | D13 - TX
28
29//
30  PWM (SPEED)
31#define MD_1_ENA 10 // LINES A, B
32#define MD_1_ENB 9  // BLOCK
33  1
34#define MD_2_ENA 11 // BLOCK 3
35#define MD_2_ENB 3  // BLOCK 2
36// DIRECTION
37  DRIVER A 
38#define MD_1_IN1 4  
39#define MD_1_IN2 2
40// DIRECTION DRIVER B
41#define
42  MD_12_IN3_IN3_IN1 5 
43#define MD_12_IN4_IN4_IN2 6
44// SENSORS
45#define SNS_1
46  17
47#define SNS_2 14
48#define SNS_3 15
49#define SNS_4 7
50#define SNS_5 8
51#define
52  SNS_6 16
53#define SNS_7 A6
54
55// Variables
56int addressI2C;
57byte dataToI2C;
58bool
59  stringComplete = false;
60String inputString = "";
61
62  // 24 speed
63  byte
64  speedArrayA [] = {30,40,50,60,80,110,140,160,180,200,220,255};
65  byte speedTrainA
66  = 0;
67
68  // Interlocking
69  unsigned long timerBlock1, timerBlock2, timerBlock3,
70  timerStation;
71  byte speedBlock1, speedBlock2, speedBlock3; 
72  
73  // Dispather
74  AWS
75  bool flag_interlocking = false;  
76  bool flag_station_open = true;    
77
78
79  // Sensors
80  unsigned long timer_protected_sensor1, timer_protected_sensor3,
81
82                timer_protected_sensor5, timer_protected_sensor7;
83  bool protected_sensor1,
84  protected_sensor3, 
85       protected_sensor5, protected_sensor7;
86  bool sensor_block1_IN,
87  sensor_block2_IN, sensor_block3_IN, 
88       sensor_block1_OUT, sensor_block2_OUT,
89  sensor_block3_OUT, 
90       sensor_OUT;
91  bool latch_stop_block1, latch_stop_block2,
92  latch_stop_block3;
93  
94  // Latches     
95  bool open_block1 = true, open_block2
96  = true, open_block3 = true;
97
98  // TURNOUTS & SET DEFAULT POSITIONS
99  bool
100  switch_A = true, switch_B = false;
101      
102
103void setup() {
104
105  // Initializie
106  Serials & I2C
107  Serial.begin(9600);
108  Bluetooth.begin(9600);
109  inputString.reserve(4);
110
111  Wire.begin(); // Set as Master
112
113  // Initialize pins
114  pinMode (MD_1_ENA,
115  OUTPUT);
116  pinMode (MD_1_ENB, OUTPUT);
117  pinMode (MD_2_ENA, OUTPUT);
118  pinMode
119  (MD_2_ENB, OUTPUT);  
120  pinMode (MD_1_IN1, OUTPUT);
121  pinMode (MD_1_IN2, OUTPUT);
122
123  pinMode (MD_12_IN3_IN3_IN1, OUTPUT);
124  pinMode (MD_12_IN4_IN4_IN2, OUTPUT);
125  
126  pinMode (SNS_1, INPUT);
127  pinMode (SNS_2, INPUT);
128  pinMode (SNS_3,
129  INPUT);
130  pinMode (SNS_4, INPUT);
131  pinMode (SNS_5, INPUT);
132  pinMode (SNS_6,
133  INPUT);
134  pinMode (SNS_7, INPUT);  
135
136  // Set PWM frequency for D3, D9,
137  D10, D11
138  // Timer 1 divisor to 256 for PWM frequency of 122.55 Hz (9, 10)
139
140  TCCR1B = TCCR1B & B11111000 | B00000100;  
141  // Timer 2 divisor to 256 for
142  PWM frequency of 122.55 Hz (3, 11)
143  TCCR2B = TCCR2B & B11111000 | B00000100;
144  
145
146  // Set default direction to FORWARD (POLARITY)  NON Interlocking
147  digitalWrite(MD_1_IN1,
148  LOW);
149  digitalWrite(MD_1_IN2, HIGH); 
150  digitalWrite(MD_12_IN3_IN3_IN1, LOW);
151
152  digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
153 
154}
155
156void loop() {
157
158
159  // ----  START PARSING INCOMING APP COMMANDS
160  if (stringComplete) {
161    //
162  RESET 
163    if (inputString =="999z") {
164      dataToI2C = 99;
165      addressI2C
166  = 2;      
167      sendDataViaI2C();
168      resetFunc();
169    }
170
171    //
172  FUNCTIONS 
173    if (inputString.charAt(0) =='a') {
174        // Speed   
175
176      if (inputString.charAt(1) =='0') {
177        if (inputString.charAt(2) =='0')
178  speedTrainA = 0;
179        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[0];
180
181        if (inputString.charAt(2) =='4') speedTrainA = speedArrayA[1];
182        if
183  (inputString.charAt(2) =='6') speedTrainA = speedArrayA[2];
184        if (inputString.charAt(2)
185  =='8') speedTrainA = speedArrayA[3]; 
186      } 
187      if (inputString.charAt(1)
188  =='1') {
189        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[4];
190
191        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[5];
192        if
193  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[6];
194        if (inputString.charAt(2)
195  =='6') speedTrainA = speedArrayA[7];
196        if (inputString.charAt(2) =='8')
197  speedTrainA = speedArrayA[8];
198      }
199      if (inputString.charAt(1) =='2')
200  {
201        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[9];
202
203        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[10];
204        if
205  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[11];         
206      }
207
208
209      // Direction and Stop
210      if (inputString.charAt(1) =='d') {
211        if
212  (inputString.charAt(2) =='f') { // (f) Forward
213          digitalWrite(MD_1_IN1,
214  LOW);
215          digitalWrite(MD_1_IN2, HIGH); 
216          digitalWrite(MD_12_IN3_IN3_IN1,
217  LOW);
218          digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
219        }
220        if
221  (inputString.charAt(2) =='b') { // (b) Backward - Interlocking
222          digitalWrite(MD_1_IN1,
223  HIGH);
224          digitalWrite(MD_1_IN2, LOW); 
225          digitalWrite(MD_12_IN3_IN3_IN1,
226  HIGH); 
227          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
228        }
229        if
230  (inputString.charAt(2) =='s') { // (s) Stop button
231          speedTrainA = 0;
232
233        } 
234
235        analogWrite(MD_1_ENA, speedTrainA); // Throttle Driver
236  A
237        
238        if (!flag_interlocking) {
239          analogWrite(MD_1_ENB,
240  speedTrainA);
241          analogWrite(MD_2_ENB, speedTrainA);
242          if (flag_station_open)
243  analogWrite(MD_2_ENA, speedTrainA); 
244          else analogWrite(MD_2_ENA,0);
245  
246        }    
247      }
248    }  
249
250    if (inputString.charAt(0) =='j')
251  {
252      // Switch A
253      if (inputString.charAt(1) =='a') { 
254        if
255  (inputString.charAt(2) =='0') { // Branch direction
256          switch_A = false;
257
258          Bluetooth.print("a0z"); // Feedback to App
259          Serial.print("a0z");
260
261          addressI2C = 2; dataToI2C = 30; sendDataViaI2C();
262        }
263        if
264  (inputString.charAt(2) =='1') { // Throw direction
265          switch_A = true;
266
267          Bluetooth.print("a1z"); // Feedback to App
268          Serial.print("a1z");
269      
270          addressI2C = 2; dataToI2C = 31; sendDataViaI2C();
271        }
272  
273      }
274
275      // Switch B
276      if (inputString.charAt(1) =='b') {
277  
278        if (inputString.charAt(2) =='0') {
279          switch_B = false;
280
281          Bluetooth.print("b0z"); 
282          Serial.print("b0z");
283          addressI2C
284  = 2; dataToI2C = 32; sendDataViaI2C();
285        }
286        if (inputString.charAt(2)
287  =='1') {
288          switch_B = true;
289          Bluetooth.print("b1z");
290
291          Serial.print("b1z");      
292          addressI2C = 2; dataToI2C =
293  33; sendDataViaI2C();
294        } 
295      }
296    }
297    
298    // AUTOMATE
299  ON | OFF
300    if (inputString.charAt(0) =='f') {
301      if (inputString.charAt(1)
302  =='a') {
303
304        if (inputString.charAt(2) =='0') {
305          flag_interlocking
306  = false;
307          speedBlock1 = 0; speedBlock2 = 0; speedBlock3 = 0;
308          addressI2C
309  = 2; dataToI2C = 50; sendDataViaI2C(); // AUTOMATE OFF
310        }
311        if
312  (inputString.charAt(2) =='1') {
313          flag_interlocking = true;
314          speedBlock1
315  = 180; speedBlock2 = 140; speedBlock3 = 160;
316          digitalWrite(MD_1_IN1,
317  HIGH);
318          digitalWrite(MD_1_IN2, LOW); 
319          digitalWrite(MD_12_IN3_IN3_IN1,
320  HIGH); 
321          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
322          protected_sensor1
323  = false; protected_sensor3 = false;
324          protected_sensor5 = false; protected_sensor7
325  = false;
326          latch_stop_block1 = false; latch_stop_block2 = false; latch_stop_block3
327  = false;
328          open_block1 = true; open_block2 = true; open_block3 = true;
329          
330          addressI2C = 2; dataToI2C = 51; sendDataViaI2C(); // AUTOMATE
331  ON
332        }
333
334        analogWrite(MD_1_ENB, speedBlock1);
335        analogWrite(MD_2_ENB,
336  speedBlock2);
337        analogWrite(MD_2_ENA, speedBlock3); 
338      }  
339    }
340
341
342    dataToI2C = 0;
343    inputString = "";
344    stringComplete = false;
345
346  }
347
348  // ----  MAIN BLOCK
349  if (flag_interlocking) {
350
351    // CHECK
352  SENSORS STATES
353
354    if (digitalRead(SNS_1) == LOW) { // BLOCK 1 | HALL
355
356      sensor_block1_IN = true;
357      open_block1 = false;
358      //Serial.println("SENSOR
359  1");
360    }
361    else sensor_block1_IN = false; 
362    if (digitalRead(SNS_2)
363  == LOW) { // HALL
364      sensor_block1_OUT = true;
365      latch_stop_block1
366  = true;
367      //Serial.println("SENSOR 2");    
368    }
369    else sensor_block1_OUT
370  = false;
371  
372    if (digitalRead(SNS_3) == HIGH) { // BLOCK 2 | IR
373      sensor_block2_IN
374  = true;
375      open_block2 = false;
376      //Serial.println("SENSOR 3");    
377
378    }
379    else sensor_block2_IN = false; 
380    if (digitalRead(SNS_4) == LOW)
381  { // HALL
382      sensor_block2_OUT = true;
383      latch_stop_block2 = true;
384
385      //Serial.println("SENSOR 4");    
386    }
387    else sensor_block2_OUT
388  = false;  
389    
390    if (digitalRead(SNS_5) == HIGH) { // BLOCK 3 | IR
391
392      sensor_block3_IN = true;
393      open_block3 = false;
394      //Serial.println("SENSOR
395  5");    
396    }
397    else sensor_block3_IN = false;
398    if (digitalRead(SNS_6)
399  == LOW) { // HALL
400      sensor_block3_OUT = true;  
401      latch_stop_block3
402  = true;
403      //Serial.println("SENSOR 6");    
404    }
405    else sensor_block3_OUT
406  = false;  
407    
408    // OUT
409    if (analogRead(SNS_7) > 550) { // ANALOGUE
410  HALL
411      sensor_OUT = true;
412      //Serial.println("SENSOR 7");
413    }
414      
415    else sensor_OUT = false;   
416  
417    // RESET BLOCK LATCHES
418
419    if (sensor_block2_IN) open_block1 = true; 
420    if (sensor_block3_IN) open_block2
421  = true;
422    if (sensor_OUT) open_block3 = true;
423
424    // RESET AUTOSTOP
425  LATCHES
426    if (sensor_block2_IN) latch_stop_block1 = false;
427    if (sensor_block3_IN)
428  latch_stop_block2 = false;        
429    if (sensor_OUT) latch_stop_block3 = false;
430
431    
432    // ----  SIGNALS
433    // SIGNAL 1
434    if (sensor_block1_IN && !protected_sensor1)
435  {
436      timer_protected_sensor1 = millis();
437      protected_sensor1 = true;
438  
439      addressI2C = 2; dataToI2C = 101; sendDataViaI2C();
440    }  
441    //
442  SIGNAL 2
443    if (sensor_block2_IN && !protected_sensor3) {
444      timer_protected_sensor3
445  = millis();
446      protected_sensor3 = true;      
447      addressI2C = 2; dataToI2C
448  = 102; sendDataViaI2C();
449    }    
450    // SIGNAL 3
451    if (sensor_block3_IN
452  && !protected_sensor5) {
453      timer_protected_sensor5 = millis();
454      protected_sensor5
455  = true;       
456      addressI2C = 2; dataToI2C = 103; sendDataViaI2C();
457    }
458  
459    // SIGNAL 4 
460    if (sensor_OUT && !protected_sensor7) {
461      timer_protected_sensor7
462  = millis();
463      timerStation = millis();
464      protected_sensor7 = true;
465  
466      flag_station_open = false;      
467      addressI2C = 2; dataToI2C =
468  104; sendDataViaI2C();
469    } 
470
471  // AUTOSTOP
472    // BLOCK 1
473    if
474  (!open_block2) {
475      if (latch_stop_block1) {
476        if (millis() > (timerBlock1
477  + 100)) {
478          timerBlock1 = millis();
479          if (speedBlock1 > 40)
480  speedBlock1 = speedBlock1 - 25;
481          else speedBlock1 = 0;
482        }
483
484      }  
485    }
486    else speedBlock1 = 180;
487
488    // BLOCK 2
489    if
490  (!open_block3) {
491      if (latch_stop_block2) {
492        if (millis() > (timerBlock2
493  + 100)) {
494          timerBlock2 = millis();
495          if (speedBlock2 > 60)
496  speedBlock2 = speedBlock2 - 30;
497          else speedBlock2 = 0;
498        }
499
500      }  
501    }
502    else speedBlock2 = 140;
503
504    // BLOCK 3
505    if
506  (!flag_station_open) {
507      if (latch_stop_block3) {
508        if (millis()
509  > (timerBlock3 + 100)) {
510          timerBlock3 = millis();
511          if (speedBlock3
512  > 40) speedBlock3 = speedBlock3 - 18;
513          else speedBlock3 = 0;
514        }
515
516      } 
517    }
518    else speedBlock3 = 160;
519    
520    analogWrite(MD_1_ENB,
521  speedBlock1);
522    analogWrite(MD_2_ENB, speedBlock2);
523    analogWrite(MD_2_ENA,
524  speedBlock3);     
525  }
526
527  // ----  TIMERS
528  if (millis() > (timer_protected_sensor1
529  + 1000)) protected_sensor1 = false;
530  if (millis() > (timer_protected_sensor3
531  + 1500)) protected_sensor3 = false;
532  if (millis() > (timer_protected_sensor5
533  + 1500)) protected_sensor5 = false;
534  if (millis() > (timer_protected_sensor7
535  + 1000)) protected_sensor7 = false;
536  if (millis() > (timerStation + 15000))
537  flag_station_open = true; // Delay 15 sec.
538
539  bluetoothEvent();
540
541}  
542
543//
544  ----------- FUNCTIONS ----------- //
545void serialEvent() {
546  if (Serial.available())
547  {
548    char inChar = (char)Serial.read();
549    inputString += inChar;
550    if
551  (inChar == 'z') {
552      stringComplete = true;
553    }
554  }
555}
556
557void
558  bluetoothEvent() {
559  if (Bluetooth.available()) {
560    char inChar = (char)Bluetooth.read();
561
562    inputString += inChar;
563    if (inChar == 'z') {
564      //Serial.println(inputString);
565  // Command from App
566      stringComplete = true;
567    }
568  }
569}
570
571void
572  sendDataViaI2C() {
573  Wire.beginTransmission(addressI2C);
574  Wire.write(dataToI2C);
575
576  Wire.endTransmission();
577}

// -------------------------------------------------- //
// WWW.ARDUINORAILWAYCONTROL.COM
                      //
// comm_urb.ino                                       //
//
  V.2.0  11/24/2019                                  //
//                                                    //
//
  SMALL INTERLOCKING                                 //
// For URB unit V.2.FINAL
                             //
// 122Hz Thrust contol                                //
//
  https://arduinorailwaycontrol.com/urb_unit.html    //
//                                                    //
//
  Author: Steve Massikker                            //
// --------------------------------------------------
  //
void(* resetFunc) (void) = 0;

#include <Wire.h>
#include <SoftwareSerial.h>

//
  Bluetooth module
SoftwareSerial Bluetooth(12, 13); // D12 - RX | D13 - TX

//
  PWM (SPEED)
#define MD_1_ENA 10 // LINES A, B
#define MD_1_ENB 9  // BLOCK
  1
#define MD_2_ENA 11 // BLOCK 3
#define MD_2_ENB 3  // BLOCK 2
// DIRECTION
  DRIVER A 
#define MD_1_IN1 4  
#define MD_1_IN2 2
// DIRECTION DRIVER B
#define
  MD_12_IN3_IN3_IN1 5 
#define MD_12_IN4_IN4_IN2 6
// SENSORS
#define SNS_1
  17
#define SNS_2 14
#define SNS_3 15
#define SNS_4 7
#define SNS_5 8
#define
  SNS_6 16
#define SNS_7 A6

// Variables
int addressI2C;
byte dataToI2C;
bool
  stringComplete = false;
String inputString = "";

  // 24 speed
  byte
  speedArrayA [] = {30,40,50,60,80,110,140,160,180,200,220,255};
  byte speedTrainA
  = 0;

  // Interlocking
  unsigned long timerBlock1, timerBlock2, timerBlock3,
  timerStation;
  byte speedBlock1, speedBlock2, speedBlock3; 
  
  // Dispather
  AWS
  bool flag_interlocking = false;  
  bool flag_station_open = true;    


  // Sensors
  unsigned long timer_protected_sensor1, timer_protected_sensor3,

                timer_protected_sensor5, timer_protected_sensor7;
  bool protected_sensor1,
  protected_sensor3, 
       protected_sensor5, protected_sensor7;
  bool sensor_block1_IN,
  sensor_block2_IN, sensor_block3_IN, 
       sensor_block1_OUT, sensor_block2_OUT,
  sensor_block3_OUT, 
       sensor_OUT;
  bool latch_stop_block1, latch_stop_block2,
  latch_stop_block3;
  
  // Latches     
  bool open_block1 = true, open_block2
  = true, open_block3 = true;

  // TURNOUTS & SET DEFAULT POSITIONS
  bool
  switch_A = true, switch_B = false;
      

void setup() {

  // Initializie
  Serials & I2C
  Serial.begin(9600);
  Bluetooth.begin(9600);
  inputString.reserve(4);

  Wire.begin(); // Set as Master

  // Initialize pins
  pinMode (MD_1_ENA,
  OUTPUT);
  pinMode (MD_1_ENB, OUTPUT);
  pinMode (MD_2_ENA, OUTPUT);
  pinMode
  (MD_2_ENB, OUTPUT);  
  pinMode (MD_1_IN1, OUTPUT);
  pinMode (MD_1_IN2, OUTPUT);

  pinMode (MD_12_IN3_IN3_IN1, OUTPUT);
  pinMode (MD_12_IN4_IN4_IN2, OUTPUT);
  
  pinMode (SNS_1, INPUT);
  pinMode (SNS_2, INPUT);
  pinMode (SNS_3,
  INPUT);
  pinMode (SNS_4, INPUT);
  pinMode (SNS_5, INPUT);
  pinMode (SNS_6,
  INPUT);
  pinMode (SNS_7, INPUT);  

  // Set PWM frequency for D3, D9,
  D10, D11
  // Timer 1 divisor to 256 for PWM frequency of 122.55 Hz (9, 10)

  TCCR1B = TCCR1B & B11111000 | B00000100;  
  // Timer 2 divisor to 256 for
  PWM frequency of 122.55 Hz (3, 11)
  TCCR2B = TCCR2B & B11111000 | B00000100;
  

  // Set default direction to FORWARD (POLARITY)  NON Interlocking
  digitalWrite(MD_1_IN1,
  LOW);
  digitalWrite(MD_1_IN2, HIGH); 
  digitalWrite(MD_12_IN3_IN3_IN1, LOW);

  digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
 
}

void loop() {


  // ----  START PARSING INCOMING APP COMMANDS
  if (stringComplete) {
    //
  RESET 
    if (inputString =="999z") {
      dataToI2C = 99;
      addressI2C
  = 2;      
      sendDataViaI2C();
      resetFunc();
    }

    //
  FUNCTIONS 
    if (inputString.charAt(0) =='a') {
        // Speed   

      if (inputString.charAt(1) =='0') {
        if (inputString.charAt(2) =='0')
  speedTrainA = 0;
        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[0];

        if (inputString.charAt(2) =='4') speedTrainA = speedArrayA[1];
        if
  (inputString.charAt(2) =='6') speedTrainA = speedArrayA[2];
        if (inputString.charAt(2)
  =='8') speedTrainA = speedArrayA[3]; 
      } 
      if (inputString.charAt(1)
  =='1') {
        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[4];

        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[5];
        if
  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[6];
        if (inputString.charAt(2)
  =='6') speedTrainA = speedArrayA[7];
        if (inputString.charAt(2) =='8')
  speedTrainA = speedArrayA[8];
      }
      if (inputString.charAt(1) =='2')
  {
        if (inputString.charAt(2) =='0') speedTrainA = speedArrayA[9];

        if (inputString.charAt(2) =='2') speedTrainA = speedArrayA[10];
        if
  (inputString.charAt(2) =='4') speedTrainA = speedArrayA[11];         
      }


      // Direction and Stop
      if (inputString.charAt(1) =='d') {
        if
  (inputString.charAt(2) =='f') { // (f) Forward
          digitalWrite(MD_1_IN1,
  LOW);
          digitalWrite(MD_1_IN2, HIGH); 
          digitalWrite(MD_12_IN3_IN3_IN1,
  LOW);
          digitalWrite(MD_12_IN4_IN4_IN2, HIGH); 
        }
        if
  (inputString.charAt(2) =='b') { // (b) Backward - Interlocking
          digitalWrite(MD_1_IN1,
  HIGH);
          digitalWrite(MD_1_IN2, LOW); 
          digitalWrite(MD_12_IN3_IN3_IN1,
  HIGH); 
          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
        }
        if
  (inputString.charAt(2) =='s') { // (s) Stop button
          speedTrainA = 0;

        } 

        analogWrite(MD_1_ENA, speedTrainA); // Throttle Driver
  A
        
        if (!flag_interlocking) {
          analogWrite(MD_1_ENB,
  speedTrainA);
          analogWrite(MD_2_ENB, speedTrainA);
          if (flag_station_open)
  analogWrite(MD_2_ENA, speedTrainA); 
          else analogWrite(MD_2_ENA,0);
  
        }    
      }
    }  

    if (inputString.charAt(0) =='j')
  {
      // Switch A
      if (inputString.charAt(1) =='a') { 
        if
  (inputString.charAt(2) =='0') { // Branch direction
          switch_A = false;

          Bluetooth.print("a0z"); // Feedback to App
          Serial.print("a0z");

          addressI2C = 2; dataToI2C = 30; sendDataViaI2C();
        }
        if
  (inputString.charAt(2) =='1') { // Throw direction
          switch_A = true;

          Bluetooth.print("a1z"); // Feedback to App
          Serial.print("a1z");
      
          addressI2C = 2; dataToI2C = 31; sendDataViaI2C();
        }
  
      }

      // Switch B
      if (inputString.charAt(1) =='b') {
  
        if (inputString.charAt(2) =='0') {
          switch_B = false;

          Bluetooth.print("b0z"); 
          Serial.print("b0z");
          addressI2C
  = 2; dataToI2C = 32; sendDataViaI2C();
        }
        if (inputString.charAt(2)
  =='1') {
          switch_B = true;
          Bluetooth.print("b1z");

          Serial.print("b1z");      
          addressI2C = 2; dataToI2C =
  33; sendDataViaI2C();
        } 
      }
    }
    
    // AUTOMATE
  ON | OFF
    if (inputString.charAt(0) =='f') {
      if (inputString.charAt(1)
  =='a') {

        if (inputString.charAt(2) =='0') {
          flag_interlocking
  = false;
          speedBlock1 = 0; speedBlock2 = 0; speedBlock3 = 0;
          addressI2C
  = 2; dataToI2C = 50; sendDataViaI2C(); // AUTOMATE OFF
        }
        if
  (inputString.charAt(2) =='1') {
          flag_interlocking = true;
          speedBlock1
  = 180; speedBlock2 = 140; speedBlock3 = 160;
          digitalWrite(MD_1_IN1,
  HIGH);
          digitalWrite(MD_1_IN2, LOW); 
          digitalWrite(MD_12_IN3_IN3_IN1,
  HIGH); 
          digitalWrite(MD_12_IN4_IN4_IN2, LOW); 
          protected_sensor1
  = false; protected_sensor3 = false;
          protected_sensor5 = false; protected_sensor7
  = false;
          latch_stop_block1 = false; latch_stop_block2 = false; latch_stop_block3
  = false;
          open_block1 = true; open_block2 = true; open_block3 = true;
          
          addressI2C = 2; dataToI2C = 51; sendDataViaI2C(); // AUTOMATE
  ON
        }

        analogWrite(MD_1_ENB, speedBlock1);
        analogWrite(MD_2_ENB,
  speedBlock2);
        analogWrite(MD_2_ENA, speedBlock3); 
      }  
    }


    dataToI2C = 0;
    inputString = "";
    stringComplete = false;

  }

  // ----  MAIN BLOCK
  if (flag_interlocking) {

    // CHECK
  SENSORS STATES

    if (digitalRead(SNS_1) == LOW) { // BLOCK 1 | HALL

      sensor_block1_IN = true;
      open_block1 = false;
      //Serial.println("SENSOR
  1");
    }
    else sensor_block1_IN = false; 
    if (digitalRead(SNS_2)
  == LOW) { // HALL
      sensor_block1_OUT = true;
      latch_stop_block1
  = true;
      //Serial.println("SENSOR 2");    
    }
    else sensor_block1_OUT
  = false;
  
    if (digitalRead(SNS_3) == HIGH) { // BLOCK 2 | IR
      sensor_block2_IN
  = true;
      open_block2 = false;
      //Serial.println("SENSOR 3");    

    }
    else sensor_block2_IN = false; 
    if (digitalRead(SNS_4) == LOW)
  { // HALL
      sensor_block2_OUT = true;
      latch_stop_block2 = true;

      //Serial.println("SENSOR 4");    
    }
    else sensor_block2_OUT
  = false;  
    
    if (digitalRead(SNS_5) == HIGH) { // BLOCK 3 | IR

      sensor_block3_IN = true;
      open_block3 = false;
      //Serial.println("SENSOR
  5");    
    }
    else sensor_block3_IN = false;
    if (digitalRead(SNS_6)
  == LOW) { // HALL
      sensor_block3_OUT = true;  
      latch_stop_block3
  = true;
      //Serial.println("SENSOR 6");    
    }
    else sensor_block3_OUT
  = false;  
    
    // OUT
    if (analogRead(SNS_7) > 550) { // ANALOGUE
  HALL
      sensor_OUT = true;
      //Serial.println("SENSOR 7");
    }
      
    else sensor_OUT = false;   
  
    // RESET BLOCK LATCHES

    if (sensor_block2_IN) open_block1 = true; 
    if (sensor_block3_IN) open_block2
  = true;
    if (sensor_OUT) open_block3 = true;

    // RESET AUTOSTOP
  LATCHES
    if (sensor_block2_IN) latch_stop_block1 = false;
    if (sensor_block3_IN)
  latch_stop_block2 = false;        
    if (sensor_OUT) latch_stop_block3 = false;

    
    // ----  SIGNALS
    // SIGNAL 1
    if (sensor_block1_IN && !protected_sensor1)
  {
      timer_protected_sensor1 = millis();
      protected_sensor1 = true;
  
      addressI2C = 2; dataToI2C = 101; sendDataViaI2C();
    }  
    //
  SIGNAL 2
    if (sensor_block2_IN && !protected_sensor3) {
      timer_protected_sensor3
  = millis();
      protected_sensor3 = true;      
      addressI2C = 2; dataToI2C
  = 102; sendDataViaI2C();
    }    
    // SIGNAL 3
    if (sensor_block3_IN
  && !protected_sensor5) {
      timer_protected_sensor5 = millis();
      protected_sensor5
  = true;       
      addressI2C = 2; dataToI2C = 103; sendDataViaI2C();
    }
  
    // SIGNAL 4 
    if (sensor_OUT && !protected_sensor7) {
      timer_protected_sensor7
  = millis();
      timerStation = millis();
      protected_sensor7 = true;
  
      flag_station_open = false;      
      addressI2C = 2; dataToI2C =
  104; sendDataViaI2C();
    } 

  // AUTOSTOP
    // BLOCK 1
    if
  (!open_block2) {
      if (latch_stop_block1) {
        if (millis() > (timerBlock1
  + 100)) {
          timerBlock1 = millis();
          if (speedBlock1 > 40)
  speedBlock1 = speedBlock1 - 25;
          else speedBlock1 = 0;
        }

      }  
    }
    else speedBlock1 = 180;

    // BLOCK 2
    if
  (!open_block3) {
      if (latch_stop_block2) {
        if (millis() > (timerBlock2
  + 100)) {
          timerBlock2 = millis();
          if (speedBlock2 > 60)
  speedBlock2 = speedBlock2 - 30;
          else speedBlock2 = 0;
        }

      }  
    }
    else speedBlock2 = 140;

    // BLOCK 3
    if
  (!flag_station_open) {
      if (latch_stop_block3) {
        if (millis()
  > (timerBlock3 + 100)) {
          timerBlock3 = millis();
          if (speedBlock3
  > 40) speedBlock3 = speedBlock3 - 18;
          else speedBlock3 = 0;
        }

      } 
    }
    else speedBlock3 = 160;
    
    analogWrite(MD_1_ENB,
  speedBlock1);
    analogWrite(MD_2_ENB, speedBlock2);
    analogWrite(MD_2_ENA,
  speedBlock3);     
  }

  // ----  TIMERS
  if (millis() > (timer_protected_sensor1
  + 1000)) protected_sensor1 = false;
  if (millis() > (timer_protected_sensor3
  + 1500)) protected_sensor3 = false;
  if (millis() > (timer_protected_sensor5
  + 1500)) protected_sensor5 = false;
  if (millis() > (timer_protected_sensor7
  + 1000)) protected_sensor7 = false;
  if (millis() > (timerStation + 15000))
  flag_station_open = true; // Delay 15 sec.

  bluetoothEvent();

}  

//
  ----------- FUNCTIONS ----------- //
void serialEvent() {
  if (Serial.available())
  {
    char inChar = (char)Serial.read();
    inputString += inChar;
    if
  (inChar == 'z') {
      stringComplete = true;
    }
  }
}

void
  bluetoothEvent() {
  if (Bluetooth.available()) {
    char inChar = (char)Bluetooth.read();

    inputString += inChar;
    if (inChar == 'z') {
      //Serial.println(inputString);
  // Command from App
      stringComplete = true;
    }
  }
}

void
  sendDataViaI2C() {
  Wire.beginTransmission(addressI2C);
  Wire.write(dataToI2C);

  Wire.endTransmission();
}

LOCAL unit sketch

arduino

1// -------------------------------------------------- //
2// WWW.ARDUINORAILWAYCONTROL.COM
3                      //
4// local_urb.ino                                      //
5//
6  V.2.0  11/24/2019                                  //
7//                                                    //
8//
9  SMALL INTERLOCKING                                 //
10// For URB unit V.2.FINAL
11                             //
12// https://arduinorailwaycontrol.com/urb_unit.html
13    //
14//                                                    //
15// Author:
16  Steve Massikker                            //
17// --------------------------------------------------
18  //
19void(* resetFunc) (void) = 0;
20
21#include <Wire.h> 
22#include <Servo.h>
23
24//
25  SERVO
26#define JUNCTION_EN 4
27Servo J1;  // TURNOUT A
28Servo J2;  // TURNOUT
29  B
30
31// SIGNALS
32#define S_LA_RED 3 // SIGNAL LINE A
33#define S_LB_RED 2
34  // SIGNAL LINE B
35#define S_B3_RED 6 // SIGNAL BLOCK 3
36#define S_B3_GRN 5
37#define
38  S_OUT_RED 10 // SIGNAL OUT
39#define S_OUT_GRN 9
40#define S_B1_RED 17 // SIGNAL
41  BLOCK 1
42#define S_B1_GRN 16
43#define S_B2_RED 15 // SIGNAL BLOCK 2
44#define
45  S_B2_GRN 14
46
47
48// RELAY
49#define RELAY_LA 13 //  LINE A
50#define RELAY_LB
51  12 //  LINE B
52
53// Variables
54byte dataFromI2C;
55unsigned long millisJunctions,
56  timerStation;
57bool switch_A = true, 
58     switch_B = false,
59     flag_blink_AB
60  = false,
61     flag_change_junc = false;
62
63bool flag_interlocking = false,
64
65     flag_station_open = true;
66     
67bool open_block1 = true, 
68     open_block2
69  = true,
70     open_block3 = true;
71
72void setup() {
73
74  // Initializie
75  Hardware Serial & I2C
76  Serial.begin(9600);
77  Wire.begin(2); // Set address
78  #2
79  Wire.onReceive(receiveI2C);
80
81  // Initialize pins  
82  pinMode (JUNCTION_EN,
83  OUTPUT);
84  pinMode (RELAY_LA, OUTPUT);
85  pinMode (RELAY_LB, OUTPUT);  
86
87  pinMode (S_LA_RED, OUTPUT);
88  pinMode (S_LB_RED, OUTPUT);
89  pinMode (S_B3_GRN,
90  OUTPUT);
91  pinMode (S_B3_RED, OUTPUT);
92  pinMode (S_B1_RED, OUTPUT);
93  pinMode
94  (S_B1_GRN, OUTPUT);  
95  pinMode (S_B2_RED, OUTPUT);
96  pinMode (S_B2_GRN, OUTPUT);
97
98  pinMode (S_OUT_RED, OUTPUT);
99  pinMode (S_OUT_GRN, OUTPUT); 
100
101  // Initialize
102  Servos
103  J1.attach(7);
104  J2.attach(8);
105
106  // Set default
107  J1.write(180);
108  J2.write(0);
109  delay(900);
110  digitalWrite(JUNCTION_EN, LOW);
111  digitalWrite(S_LA_RED,
112  LOW); 
113  digitalWrite(S_LB_RED, HIGH);   
114  digitalWrite(S_B1_GRN, LOW);
115
116  digitalWrite(S_B1_RED, HIGH);
117  digitalWrite(S_B2_GRN, LOW);
118  digitalWrite(S_B2_RED,
119  HIGH);
120  digitalWrite(S_B3_GRN, LOW);
121  digitalWrite(S_B3_RED, HIGH);
122
123  digitalWrite(S_OUT_GRN, HIGH);    
124  digitalWrite(S_OUT_RED, LOW);
125  digitalWrite(RELAY_LA,
126  LOW); // Line A is ON 
127  digitalWrite(RELAY_LB, HIGH); // Line B is OFF
128}
129
130void
131  loop() {
132
133// ---- COMMAND PARSING
134  if (dataFromI2C != 0) {
135    
136
137    switch (dataFromI2C) {
138
139      // RESET
140      case 99: resetFunc();
141  break;
142
143      // SWITCH A
144      case 30: J1.write(0);
145           delay(50);
146
147           switch_A = false;
148           flag_change_junc = true;
149           digitalWrite(JUNCTION_EN,
150  HIGH);
151           Serial.println("SWITCH A Branch");
152           millisJunctions
153  = millis();
154           break;
155
156      case 31: J1.write(180);
157           delay(50);
158
159           switch_A = true;
160           flag_change_junc = true;         
161
162           digitalWrite(JUNCTION_EN, HIGH);
163           Serial.println("SWITCH
164  A Straight");         
165           millisJunctions = millis();
166           break;
167
168
169      // SWITCH B
170      case 32: J2.write(0);
171           delay(50);
172           switch_B
173  = false; 
174           flag_change_junc = true;             
175           digitalWrite(JUNCTION_EN,
176  HIGH);
177           Serial.println("SWITCH B Branch");
178           millisJunctions
179  = millis();
180           break;
181
182      case 33: J2.write(180);
183           delay(50);
184
185           switch_B = true; 
186           flag_change_junc = true;             
187
188           digitalWrite(JUNCTION_EN, HIGH);
189           Serial.println("SWITCH
190  B Straight");
191           millisJunctions= millis();
192           break;
193
194
195      // MODE
196      case 50: flag_interlocking = false;  
197           break;
198
199      case 51: flag_interlocking = true;  
200           break; 
201
202      //
203  BLOCKS STATE
204      case 101: open_block1 = false;
205           Serial.println("BLOCK
206  1");
207           break;
208      case 102: open_block2 = false;
209           open_block1
210  = true; 
211           Serial.println("BLOCK 2");           
212           break;
213
214      case 103: open_block3 = false;
215           open_block2 = true;
216           Serial.println("BLOCK
217  3");
218           break;
219      case 104: open_block3 = true;
220           flag_station_open
221  = false;
222           timerStation = millis();
223           Serial.println("OUT");
224
225           break;
226    }
227     
228    dataFromI2C = 0;
229  }
230
231// ----
232  SIGNALS
233  // BLOCK 1
234  if (flag_interlocking) {
235    if (open_block1) {
236
237      digitalWrite(S_B1_GRN, HIGH); 
238      digitalWrite(S_B1_RED, LOW);     
239
240    }
241    else {
242      digitalWrite(S_B1_GRN, LOW); 
243      digitalWrite(S_B1_RED,
244  HIGH); 
245    }
246  // BLOCK 2
247    if (open_block2) {
248      digitalWrite(S_B2_GRN,
249  HIGH); 
250      digitalWrite(S_B2_RED, LOW);     
251    }
252    else {
253      digitalWrite(S_B2_GRN,
254  LOW); 
255      digitalWrite(S_B2_RED, HIGH); 
256    }
257  // BLOCK 3
258    if
259  (open_block3) {
260      digitalWrite(S_B3_GRN, HIGH); 
261      digitalWrite(S_B3_RED,
262  LOW);     
263    }
264    else {
265      digitalWrite(S_B3_GRN, LOW); 
266      digitalWrite(S_B3_RED,
267  HIGH); 
268    }
269  }
270  else {
271    digitalWrite(S_B1_GRN, LOW);
272    digitalWrite(S_B1_RED,
273  HIGH);
274    digitalWrite(S_B2_GRN, LOW);
275    digitalWrite(S_B2_RED, HIGH);
276
277    digitalWrite(S_B3_GRN, LOW);
278    digitalWrite(S_B3_RED, HIGH);
279  }   
280
281
282  // OUT
283  if (flag_station_open) {
284    digitalWrite(S_OUT_GRN, HIGH);    
285
286    digitalWrite(S_OUT_RED, LOW);
287  }
288  else {
289    digitalWrite(S_OUT_GRN,
290  LOW);    
291    digitalWrite(S_OUT_RED, HIGH);
292  }
293
294// ---- RELAY
295
296  if (flag_change_junc) {
297
298  	if (switch_A && !switch_B) { // Line A
299
300      digitalWrite(S_LA_RED, LOW);
301      digitalWrite(S_LB_RED, HIGH); // RED
302     
303      digitalWrite(RELAY_LA, LOW);
304      digitalWrite(RELAY_LB, HIGH);
305  
306      flag_blink_AB = false;
307  	}
308  	else if (!switch_A && switch_B)
309  { // Line B
310      digitalWrite(S_LA_RED, HIGH); // RED
311      digitalWrite(S_LB_RED,
312  LOW);       
313      digitalWrite(RELAY_LA, HIGH); 
314      digitalWrite(RELAY_LB,
315  LOW); 
316      flag_blink_AB = false;     
317  	}
318  	else { // Undefined
319
320      digitalWrite(RELAY_LA, HIGH); 
321      digitalWrite(RELAY_LB, HIGH); 
322
323      flag_blink_AB = true;     
324  	}
325 
326    flag_change_junc = false;
327  
328  } 
329
330  if (millis() > (millisJunctions + 900)) digitalWrite(JUNCTION_EN,
331  LOW);
332  if (millis() > (timerStation + 15000)) flag_station_open = true; // Delay
333  15 sec.  
334
335  if (flag_blink_AB) {
336  	static bool tick_blink;
337    static
338  unsigned long blinkMillis;
339    if (millis() > (blinkMillis + 500)) { // 500 -
340  blinking optimal period
341      tick_blink = !tick_blink;
342      blinkMillis
343  = millis();
344    }
345    digitalWrite(S_LA_RED, tick_blink);
346    digitalWrite(S_LB_RED,
347  !tick_blink);
348  }
349
350}
351
352// ----------- FUNCTIONS ----------- //
353
354void
355  receiveI2C(int howMany) {
356  while (Wire.available() > 0) {
357    dataFromI2C
358  = Wire.read();
359  }
360}
361

// -------------------------------------------------- //
// WWW.ARDUINORAILWAYCONTROL.COM
                      //
// local_urb.ino                                      //
//
  V.2.0  11/24/2019                                  //
//                                                    //
//
  SMALL INTERLOCKING                                 //
// For URB unit V.2.FINAL
                             //
// https://arduinorailwaycontrol.com/urb_unit.html
    //
//                                                    //
// Author:
  Steve Massikker                            //
// --------------------------------------------------
  //
void(* resetFunc) (void) = 0;

#include <Wire.h> 
#include <Servo.h>

//
  SERVO
#define JUNCTION_EN 4
Servo J1;  // TURNOUT A
Servo J2;  // TURNOUT
  B

// SIGNALS
#define S_LA_RED 3 // SIGNAL LINE A
#define S_LB_RED 2
  // SIGNAL LINE B
#define S_B3_RED 6 // SIGNAL BLOCK 3
#define S_B3_GRN 5
#define
  S_OUT_RED 10 // SIGNAL OUT
#define S_OUT_GRN 9
#define S_B1_RED 17 // SIGNAL
  BLOCK 1
#define S_B1_GRN 16
#define S_B2_RED 15 // SIGNAL BLOCK 2
#define
  S_B2_GRN 14


// RELAY
#define RELAY_LA 13 //  LINE A
#define RELAY_LB
  12 //  LINE B

// Variables
byte dataFromI2C;
unsigned long millisJunctions,
  timerStation;
bool switch_A = true, 
     switch_B = false,
     flag_blink_AB
  = false,
     flag_change_junc = false;

bool flag_interlocking = false,

     flag_station_open = true;
     
bool open_block1 = true, 
     open_block2
  = true,
     open_block3 = true;

void setup() {

  // Initializie
  Hardware Serial & I2C
  Serial.begin(9600);
  Wire.begin(2); // Set address
  #2
  Wire.onReceive(receiveI2C);

  // Initialize pins  
  pinMode (JUNCTION_EN,
  OUTPUT);
  pinMode (RELAY_LA, OUTPUT);
  pinMode (RELAY_LB, OUTPUT);  

  pinMode (S_LA_RED, OUTPUT);
  pinMode (S_LB_RED, OUTPUT);
  pinMode (S_B3_GRN,
  OUTPUT);
  pinMode (S_B3_RED, OUTPUT);
  pinMode (S_B1_RED, OUTPUT);
  pinMode
  (S_B1_GRN, OUTPUT);  
  pinMode (S_B2_RED, OUTPUT);
  pinMode (S_B2_GRN, OUTPUT);

  pinMode (S_OUT_RED, OUTPUT);
  pinMode (S_OUT_GRN, OUTPUT); 

  // Initialize
  Servos
  J1.attach(7);
  J2.attach(8);

  // Set default
  J1.write(180);
  J2.write(0);
  delay(900);
  digitalWrite(JUNCTION_EN, LOW);
  digitalWrite(S_LA_RED,
  LOW); 
  digitalWrite(S_LB_RED, HIGH);   
  digitalWrite(S_B1_GRN, LOW);

  digitalWrite(S_B1_RED, HIGH);
  digitalWrite(S_B2_GRN, LOW);
  digitalWrite(S_B2_RED,
  HIGH);
  digitalWrite(S_B3_GRN, LOW);
  digitalWrite(S_B3_RED, HIGH);

  digitalWrite(S_OUT_GRN, HIGH);    
  digitalWrite(S_OUT_RED, LOW);
  digitalWrite(RELAY_LA,
  LOW); // Line A is ON 
  digitalWrite(RELAY_LB, HIGH); // Line B is OFF
}

void
  loop() {

// ---- COMMAND PARSING
  if (dataFromI2C != 0) {
    

    switch (dataFromI2C) {

      // RESET
      case 99: resetFunc();
  break;

      // SWITCH A
      case 30: J1.write(0);
           delay(50);

           switch_A = false;
           flag_change_junc = true;
           digitalWrite(JUNCTION_EN,
  HIGH);
           Serial.println("SWITCH A Branch");
           millisJunctions
  = millis();
           break;

      case 31: J1.write(180);
           delay(50);

           switch_A = true;
           flag_change_junc = true;         

           digitalWrite(JUNCTION_EN, HIGH);
           Serial.println("SWITCH
  A Straight");         
           millisJunctions = millis();
           break;


      // SWITCH B
      case 32: J2.write(0);
           delay(50);
           switch_B
  = false; 
           flag_change_junc = true;             
           digitalWrite(JUNCTION_EN,
  HIGH);
           Serial.println("SWITCH B Branch");
           millisJunctions
  = millis();
           break;

      case 33: J2.write(180);
           delay(50);

           switch_B = true; 
           flag_change_junc = true;             

           digitalWrite(JUNCTION_EN, HIGH);
           Serial.println("SWITCH
  B Straight");
           millisJunctions= millis();
           break;


      // MODE
      case 50: flag_interlocking = false;  
           break;

      case 51: flag_interlocking = true;  
           break; 

      //
  BLOCKS STATE
      case 101: open_block1 = false;
           Serial.println("BLOCK
  1");
           break;
      case 102: open_block2 = false;
           open_block1
  = true; 
           Serial.println("BLOCK 2");           
           break;

      case 103: open_block3 = false;
           open_block2 = true;
           Serial.println("BLOCK
  3");
           break;
      case 104: open_block3 = true;
           flag_station_open
  = false;
           timerStation = millis();
           Serial.println("OUT");

           break;
    }
     
    dataFromI2C = 0;
  }

// ----
  SIGNALS
  // BLOCK 1
  if (flag_interlocking) {
    if (open_block1) {

      digitalWrite(S_B1_GRN, HIGH); 
      digitalWrite(S_B1_RED, LOW);     

    }
    else {
      digitalWrite(S_B1_GRN, LOW); 
      digitalWrite(S_B1_RED,
  HIGH); 
    }
  // BLOCK 2
    if (open_block2) {
      digitalWrite(S_B2_GRN,
  HIGH); 
      digitalWrite(S_B2_RED, LOW);     
    }
    else {
      digitalWrite(S_B2_GRN,
  LOW); 
      digitalWrite(S_B2_RED, HIGH); 
    }
  // BLOCK 3
    if
  (open_block3) {
      digitalWrite(S_B3_GRN, HIGH); 
      digitalWrite(S_B3_RED,
  LOW);     
    }
    else {
      digitalWrite(S_B3_GRN, LOW); 
      digitalWrite(S_B3_RED,
  HIGH); 
    }
  }
  else {
    digitalWrite(S_B1_GRN, LOW);
    digitalWrite(S_B1_RED,
  HIGH);
    digitalWrite(S_B2_GRN, LOW);
    digitalWrite(S_B2_RED, HIGH);

    digitalWrite(S_B3_GRN, LOW);
    digitalWrite(S_B3_RED, HIGH);
  }   


  // OUT
  if (flag_station_open) {
    digitalWrite(S_OUT_GRN, HIGH);    

    digitalWrite(S_OUT_RED, LOW);
  }
  else {
    digitalWrite(S_OUT_GRN,
  LOW);    
    digitalWrite(S_OUT_RED, HIGH);
  }

// ---- RELAY

  if (flag_change_junc) {

  	if (switch_A && !switch_B) { // Line A

      digitalWrite(S_LA_RED, LOW);
      digitalWrite(S_LB_RED, HIGH); // RED
     
      digitalWrite(RELAY_LA, LOW);
      digitalWrite(RELAY_LB, HIGH);
  
      flag_blink_AB = false;
  	}
  	else if (!switch_A && switch_B)
  { // Line B
      digitalWrite(S_LA_RED, HIGH); // RED
      digitalWrite(S_LB_RED,
  LOW);       
      digitalWrite(RELAY_LA, HIGH); 
      digitalWrite(RELAY_LB,
  LOW); 
      flag_blink_AB = false;     
  	}
  	else { // Undefined

      digitalWrite(RELAY_LA, HIGH); 
      digitalWrite(RELAY_LB, HIGH); 

      flag_blink_AB = true;     
  	}
 
    flag_change_junc = false;
  
  } 

  if (millis() > (millisJunctions + 900)) digitalWrite(JUNCTION_EN,
  LOW);
  if (millis() > (timerStation + 15000)) flag_station_open = true; // Delay
  15 sec.  

  if (flag_blink_AB) {
  	static bool tick_blink;
    static
  unsigned long blinkMillis;
    if (millis() > (blinkMillis + 500)) { // 500 -
  blinking optimal period
      tick_blink = !tick_blink;
      blinkMillis
  = millis();
    }
    digitalWrite(S_LA_RED, tick_blink);
    digitalWrite(S_LB_RED,
  !tick_blink);
  }

}

// ----------- FUNCTIONS ----------- //

void
  receiveI2C(int howMany) {
  while (Wire.available() > 0) {
    dataFromI2C
  = Wire.read();
  }
}

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Track Plan

Circuit of Interlocking system

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