Multitasking And Real-Time Arduino System

This simple project shows how Arduino can be used with a RTOS. A special version of Arduino called ARTe was used for software development.

May 16, 2017

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real-time

multiprocessing

Components and supplies

Ultrasonic Sensor - HC-SR04 (Generic)

Temperature Sensor

Arduino UNO

LED (generic)

Apps and platforms

ARTe (Arduino Real-Time extension)

Project description

Code

Multitasking-RealTime-Arduino-System

This simple project shows how Arduino can be used with a real time operating system (Erika). A special version of Arduino called ARTe was used for software development ( http://retis.sssup.it/?q=arte ). ARTe (Arduino Real-Time extension) is an extension to the Arduino framework that supports multitasking and real-time preemptive scheduling. Thanks to ARTe, the user can easily specify and run multiple concurrent loops at differents rates, in addition to the single execution cycle provided by the standard Arduino framework. Today ARTE supports the most popular platforms: Arduino UNO and Arduino DUE. In addition to the single loop present in the standard Arduino approach, the user can easily specify a number of concurrent loops to be executed at specific rates. Concurrency and real-time scheduling is provided by the ERIKA Enterprise (http://erika.tuxfamily.org/drupal/) open-source real-time kernel. Loops can use the standard Arduino libraries, which have been enhanced to guarantee mutual exclusion in the access of shared data structures. The impact of ARTe in terms of footprint and runtime overhead has beed evaluated by extensive tests and resulted to be negligible. In this project was used to run 3 periodic processes that handle different activities. A process for managing every 3 seconds the acquisition of the distance through the sensor HC-SR04. Another process for flashing a LED every 7 seconds. A final process to read the temperature returned by the LM35 sensor expressed in degrees Celsius is executed every 11 seconds. All processes are managed in real time mode.

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Multitasking and Real-Time Arduino Processing

arduino

1//Pin definition
2static int trigger = 9; // Pin HC-SR04
3static int  echo = 8; // Pin HC-SR04
4static int led_HC = 10; // Pin HC-SR04
5static int  led_pulsed = 13; // Timed pulsed led
6static int led_temperature = 12; // Led  to temperature overflow
7static int LM35_analogPin = 0; // analog pin for temperature  sensor
8
9
10// Variables for calculating the distance with sensor HC-SR04
11long  duration; // Flight time of signal
12long distance;  // Calculated distance 
13float  temp_C; // temperature variable (Celsius degrees)
14
15void setup() {
16  //Serial  communication
17  Serial.begin(9600);
18
19  //Pin setup
20  pinMode(trigger,  OUTPUT);
21  pinMode(echo, INPUT);
22  pinMode(led_HC, OUTPUT);
23  pinMode(led_pulsed,  OUTPUT);
24  pinMode(led_temperature, OUTPUT);
25
26  digitalWrite(echo, LOW);
27  digitalWrite(trigger, LOW);
28  digitalWrite(led_HC, LOW);
29  digitalWrite(led_pulsed,  LOW);
30  digitalWrite(led_temperature, LOW);
31
32  //Analog input
33  analogReference(INTERNAL);  // prendo la misura analogica di riferimento di Arduino a 1.1V
34
35  //Variable  initialization of the distance
36  duration = 0;
37  distance = 0;
38}
39
40void  loop() {
41}
42
43void loop1(3000) {
44  //Send a HIGH pulse to the trigger  pin
45  digitalWrite(trigger, HIGH);
46  //I leave it to the HIGH value for 10  microseconds
47  delayMicroseconds(10);
48  //I carry it back to the LOW state
49  digitalWrite(trigger, LOW);
50
51  //I get the number of microseconds for which  the echo PIN is left in HIGH state
52  duration = pulseIn(echo, HIGH);
53
54  /*Sound velocity is 340 meters per second, or 29 microseconds per cent.
55    Our  impulse travels back and forth, so to calculate the distance
56   Between the sensor  and our obstacle we need to do:*/
57  distance = duration / 29 / 2;
58
59  //  Turn on the led if there is an obstacle at a distance of less than 10 cm
60  if  (distance < 10) {
61    digitalWrite(led_HC, HIGH);
62  }
63  else {
64    digitalWrite(led_HC,  LOW);
65  }
66  // Print on the serial buffer
67  Serial.print("duration : ");
68  Serial.print(duration);
69  Serial.print(" - distance : ");
70  Serial.println(distance);
71}
72
73void  loop2(7000) {
74  int i;
75  Serial.println("Pulsed LED");
76  // Code for  the flashing of the led
77  for (i = 0; i < 5; i++)
78  {
79    digitalWrite(led_pulsed,  HIGH);
80    delay(500);
81    digitalWrite(led_pulsed, LOW);
82    delay(500);
83  }
84}
85
86void loop3(11000) {
87  float sum_temp = 0;
88  float average_temp  = 0;
89  /* Acquire 3 values from the sensor every 500 milliseconds.
90     Through  an appropriate conversion I get the measure in degrees Celsius.
91     Calculate  the average of subsequent measurements.*/
92  for (int i = 0; i < 3; i++){  
93    delay(500);
94    temp_C = (1.1 * analogRead(LM35_analogPin) * 100.0) / 1024;
95    sum_temp += temp_C;
96  }
97  average_temp = sum_temp / 3;
98  // If the  temperature is greater than 23 degrees, turn on the led
99  if (average_temp >  23) {
100    digitalWrite(led_temperature, HIGH);
101  }
102  else {
103    digitalWrite(led_temperature,  LOW);
104  }
105  Serial.print("Temperature : ");
106  Serial.println(average_temp);
107}
108
109
110
111

//Pin definition
static int trigger = 9; // Pin HC-SR04
static int  echo = 8; // Pin HC-SR04
static int led_HC = 10; // Pin HC-SR04
static int  led_pulsed = 13; // Timed pulsed led
static int led_temperature = 12; // Led  to temperature overflow
static int LM35_analogPin = 0; // analog pin for temperature  sensor


// Variables for calculating the distance with sensor HC-SR04
long  duration; // Flight time of signal
long distance;  // Calculated distance 
float  temp_C; // temperature variable (Celsius degrees)

void setup() {
  //Serial  communication
  Serial.begin(9600);

  //Pin setup
  pinMode(trigger,  OUTPUT);
  pinMode(echo, INPUT);
  pinMode(led_HC, OUTPUT);
  pinMode(led_pulsed,  OUTPUT);
  pinMode(led_temperature, OUTPUT);

  digitalWrite(echo, LOW);
  digitalWrite(trigger, LOW);
  digitalWrite(led_HC, LOW);
  digitalWrite(led_pulsed,  LOW);
  digitalWrite(led_temperature, LOW);

  //Analog input
  analogReference(INTERNAL);  // prendo la misura analogica di riferimento di Arduino a 1.1V

  //Variable  initialization of the distance
  duration = 0;
  distance = 0;
}

void  loop() {
}

void loop1(3000) {
  //Send a HIGH pulse to the trigger  pin
  digitalWrite(trigger, HIGH);
  //I leave it to the HIGH value for 10  microseconds
  delayMicroseconds(10);
  //I carry it back to the LOW state
  digitalWrite(trigger, LOW);

  //I get the number of microseconds for which  the echo PIN is left in HIGH state
  duration = pulseIn(echo, HIGH);

  /*Sound velocity is 340 meters per second, or 29 microseconds per cent.
    Our  impulse travels back and forth, so to calculate the distance
   Between the sensor  and our obstacle we need to do:*/
  distance = duration / 29 / 2;

  //  Turn on the led if there is an obstacle at a distance of less than 10 cm
  if  (distance < 10) {
    digitalWrite(led_HC, HIGH);
  }
  else {
    digitalWrite(led_HC,  LOW);
  }
  // Print on the serial buffer
  Serial.print("duration : ");
  Serial.print(duration);
  Serial.print(" - distance : ");
  Serial.println(distance);
}

void  loop2(7000) {
  int i;
  Serial.println("Pulsed LED");
  // Code for  the flashing of the led
  for (i = 0; i < 5; i++)
  {
    digitalWrite(led_pulsed,  HIGH);
    delay(500);
    digitalWrite(led_pulsed, LOW);
    delay(500);
  }
}

void loop3(11000) {
  float sum_temp = 0;
  float average_temp  = 0;
  /* Acquire 3 values from the sensor every 500 milliseconds.
     Through  an appropriate conversion I get the measure in degrees Celsius.
     Calculate  the average of subsequent measurements.*/
  for (int i = 0; i < 3; i++){  
    delay(500);
    temp_C = (1.1 * analogRead(LM35_analogPin) * 100.0) / 1024;
    sum_temp += temp_C;
  }
  average_temp = sum_temp / 3;
  // If the  temperature is greater than 23 degrees, turn on the led
  if (average_temp >  23) {
    digitalWrite(led_temperature, HIGH);
  }
  else {
    digitalWrite(led_temperature,  LOW);
  }
  Serial.print("Temperature : ");
  Serial.println(average_temp);
}

Multitasking-RealTime-Arduino-System

no description/ Read More

Latest commit to the master branch on Invalid date

Download as a zip

Multitasking and Real-Time Arduino Processing

arduino

1//Pin definition
2static int trigger = 9; // Pin HC-SR04
3static int
4  echo = 8; // Pin HC-SR04
5static int led_HC = 10; // Pin HC-SR04
6static int
7  led_pulsed = 13; // Timed pulsed led
8static int led_temperature = 12; // Led
9  to temperature overflow
10static int LM35_analogPin = 0; // analog pin for temperature
11  sensor
12
13
14// Variables for calculating the distance with sensor HC-SR04
15long
16  duration; // Flight time of signal
17long distance;  // Calculated distance 
18float
19  temp_C; // temperature variable (Celsius degrees)
20
21void setup() {
22  //Serial
23  communication
24  Serial.begin(9600);
25
26  //Pin setup
27  pinMode(trigger,
28  OUTPUT);
29  pinMode(echo, INPUT);
30  pinMode(led_HC, OUTPUT);
31  pinMode(led_pulsed,
32  OUTPUT);
33  pinMode(led_temperature, OUTPUT);
34
35  digitalWrite(echo, LOW);
36
37  digitalWrite(trigger, LOW);
38  digitalWrite(led_HC, LOW);
39  digitalWrite(led_pulsed,
40  LOW);
41  digitalWrite(led_temperature, LOW);
42
43  //Analog input
44  analogReference(INTERNAL);
45  // prendo la misura analogica di riferimento di Arduino a 1.1V
46
47  //Variable
48  initialization of the distance
49  duration = 0;
50  distance = 0;
51}
52
53void
54  loop() {
55}
56
57void loop1(3000) {
58  //Send a HIGH pulse to the trigger
59  pin
60  digitalWrite(trigger, HIGH);
61  //I leave it to the HIGH value for 10
62  microseconds
63  delayMicroseconds(10);
64  //I carry it back to the LOW state
65
66  digitalWrite(trigger, LOW);
67
68  //I get the number of microseconds for which
69  the echo PIN is left in HIGH state
70  duration = pulseIn(echo, HIGH);
71
72
73  /*Sound velocity is 340 meters per second, or 29 microseconds per cent.
74    Our
75  impulse travels back and forth, so to calculate the distance
76   Between the sensor
77  and our obstacle we need to do:*/
78  distance = duration / 29 / 2;
79
80  //
81  Turn on the led if there is an obstacle at a distance of less than 10 cm
82  if
83  (distance < 10) {
84    digitalWrite(led_HC, HIGH);
85  }
86  else {
87    digitalWrite(led_HC,
88  LOW);
89  }
90  // Print on the serial buffer
91  Serial.print("duration : ");
92
93  Serial.print(duration);
94  Serial.print(" - distance : ");
95  Serial.println(distance);
96}
97
98void
99  loop2(7000) {
100  int i;
101  Serial.println("Pulsed LED");
102  // Code for
103  the flashing of the led
104  for (i = 0; i < 5; i++)
105  {
106    digitalWrite(led_pulsed,
107  HIGH);
108    delay(500);
109    digitalWrite(led_pulsed, LOW);
110    delay(500);
111
112  }
113}
114
115void loop3(11000) {
116  float sum_temp = 0;
117  float average_temp
118  = 0;
119  /* Acquire 3 values from the sensor every 500 milliseconds.
120     Through
121  an appropriate conversion I get the measure in degrees Celsius.
122     Calculate
123  the average of subsequent measurements.*/
124  for (int i = 0; i < 3; i++){  
125
126    delay(500);
127    temp_C = (1.1 * analogRead(LM35_analogPin) * 100.0) / 1024;
128
129    sum_temp += temp_C;
130  }
131  average_temp = sum_temp / 3;
132  // If the
133  temperature is greater than 23 degrees, turn on the led
134  if (average_temp >
135  23) {
136    digitalWrite(led_temperature, HIGH);
137  }
138  else {
139    digitalWrite(led_temperature,
140  LOW);
141  }
142  Serial.print("Temperature : ");
143  Serial.println(average_temp);
144}
145
146
147
148

//Pin definition
static int trigger = 9; // Pin HC-SR04
static int
  echo = 8; // Pin HC-SR04
static int led_HC = 10; // Pin HC-SR04
static int
  led_pulsed = 13; // Timed pulsed led
static int led_temperature = 12; // Led
  to temperature overflow
static int LM35_analogPin = 0; // analog pin for temperature
  sensor


// Variables for calculating the distance with sensor HC-SR04
long
  duration; // Flight time of signal
long distance;  // Calculated distance 
float
  temp_C; // temperature variable (Celsius degrees)

void setup() {
  //Serial
  communication
  Serial.begin(9600);

  //Pin setup
  pinMode(trigger,
  OUTPUT);
  pinMode(echo, INPUT);
  pinMode(led_HC, OUTPUT);
  pinMode(led_pulsed,
  OUTPUT);
  pinMode(led_temperature, OUTPUT);

  digitalWrite(echo, LOW);

  digitalWrite(trigger, LOW);
  digitalWrite(led_HC, LOW);
  digitalWrite(led_pulsed,
  LOW);
  digitalWrite(led_temperature, LOW);

  //Analog input
  analogReference(INTERNAL);
  // prendo la misura analogica di riferimento di Arduino a 1.1V

  //Variable
  initialization of the distance
  duration = 0;
  distance = 0;
}

void
  loop() {
}

void loop1(3000) {
  //Send a HIGH pulse to the trigger
  pin
  digitalWrite(trigger, HIGH);
  //I leave it to the HIGH value for 10
  microseconds
  delayMicroseconds(10);
  //I carry it back to the LOW state

  digitalWrite(trigger, LOW);

  //I get the number of microseconds for which
  the echo PIN is left in HIGH state
  duration = pulseIn(echo, HIGH);


  /*Sound velocity is 340 meters per second, or 29 microseconds per cent.
    Our
  impulse travels back and forth, so to calculate the distance
   Between the sensor
  and our obstacle we need to do:*/
  distance = duration / 29 / 2;

  //
  Turn on the led if there is an obstacle at a distance of less than 10 cm
  if
  (distance < 10) {
    digitalWrite(led_HC, HIGH);
  }
  else {
    digitalWrite(led_HC,
  LOW);
  }
  // Print on the serial buffer
  Serial.print("duration : ");

  Serial.print(duration);
  Serial.print(" - distance : ");
  Serial.println(distance);
}

void
  loop2(7000) {
  int i;
  Serial.println("Pulsed LED");
  // Code for
  the flashing of the led
  for (i = 0; i < 5; i++)
  {
    digitalWrite(led_pulsed,
  HIGH);
    delay(500);
    digitalWrite(led_pulsed, LOW);
    delay(500);

  }
}

void loop3(11000) {
  float sum_temp = 0;
  float average_temp
  = 0;
  /* Acquire 3 values from the sensor every 500 milliseconds.
     Through
  an appropriate conversion I get the measure in degrees Celsius.
     Calculate
  the average of subsequent measurements.*/
  for (int i = 0; i < 3; i++){  

    delay(500);
    temp_C = (1.1 * analogRead(LM35_analogPin) * 100.0) / 1024;

    sum_temp += temp_C;
  }
  average_temp = sum_temp / 3;
  // If the
  temperature is greater than 23 degrees, turn on the led
  if (average_temp >
  23) {
    digitalWrite(led_temperature, HIGH);
  }
  else {
    digitalWrite(led_temperature,
  LOW);
  }
  Serial.print("Temperature : ");
  Serial.println(average_temp);
}

Downloadable files

Circuit Diagram

Electronic circuit of the components used. This schema has been designed to work properly with the implemented Arduino code. If the layout of the components is changed, you must change the pin statement in the Arduino code.

Circuit Diagram

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