Implementing Multiple Mixed Switch Types By Polling

1/*
2   Ron D Bentley, Stafford, UK
3   Feb 2021
4
5   Reading  Multiple Switch Types, using simple polling
6   '''''''''''''''''''''''''''''''''''''''''''''''''''
7
8   This example and code is in the public domain and may be used without restriction  and
9   without warranty.
10
11   This sketch will reliably read any number  of button and/or toggle switches by polling each of
12   them in turn.  Once a  switch is activated the main code loop will switch
13   to user provided code to  handle the purpose of the switch.  This is controlled
14   via a switch control  struct(ure) and associated main loop switch-case code.
15
16   The sketch layout  is straight forward and process code for each switch can be added
17   where indicated  within the main loop, under the respective switch-case section for a
18   button  switch.
19
20   Configurability:
21   1. Number of switches - the implementation  is such that each switch is
22      allocated to a digital pin.  The sketch will  therefore support as many
23      switches as a microcontroller can provide digital  inputs.
24      This example sketch is configured, 'out-of-the-box' (OOTB),for  six switches,
25      3 x button switches plus 3 x toggle swith, but more may be  added:
26
27      a. change the macro definition '#define num_switches' to be  the total number of
28         switches to be connected
29      b. for each switch,  decide its circuit type and allocate it to a digital pin
30      c. in the 'Switch  to Pin Macro Definition List' add new switch macro
31         definitions, one  for each additional switch,
32         for example:
33         '#define button_switch_?  <pin number>',
34         '#define toggle_switch_?  <pin number>',
35         etc
36      d. in the 'Switch Control Sruct(ure) Declaration' add further preset data  to the
37         'switches' data struct(ure), for example:
38         '...,button_switch_?,  circuit_?,...',
39         '...,toggle_switch_?, circuit_?,...',
40         etc.
41
42   For a fuller appreciation of button switch fundementals see the tutorial 'Understanding
43   and Using Button Switches':
44   https://create.arduino.cc/projecthub/ronbentley1/understanding-and-using-button-switches-2ffe6c?ref=platform&ref_id=424_trending___&offset=2
45*/
46//  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
47//  These declarations are specifically for defining and controlling the attached switches
48//  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
49
50#define  circuit_C1           INPUT   // switch circuit requires an external pull down 10k  ohm resistor
51#define circuit_C2    INPUT_PULLUP   // switch type reqires no other  components beyond the button switch
52
53#define debounce             10      //  number of millisecs to wait for a switch to settle once activated
54#define switched           true      // signifies switch has been pressed/switch cycle complete
55#define  on                 true      // used for toggle switch staus
56#define not_used           true      // helps self document code
57
58#define button_switch        1       // differentiates switch type
59#define toggle_switch        2       //  toggle switches are NOT used in this example sketch - future use
60
61#define  num_switches         6       // number of button switches connected
62
63// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
64//  %       Switch to Pin Macro Definition List         %
65// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
66//  Associate swithes each with a digital pin.
67// Add further definitions here if  adding more switches.
68// Note that digital pins allocated are arbitary, any
69//  available pin will do, or remove any not required.
70// The naming convention offered  here helps to self
71// document the sketch.
72
73#define button_switch_1      2
74#define  button_switch_2      3
75#define button_switch_3      4
76
77#define toggle_switch_1      5
78#define toggle_switch_2      6
79#define toggle_switch_3      7
80
81//  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
82//  %                   Switch Control Sruct(ure) Declaration                 %
83//  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
84//  Now set up the configuration data for each individual switch to be used by
85//  the switch read functions and to generally define the nature of the switch.
86//
87struct  switch_control {
88  int  switch_type;               // type of switch connected
89  int  switch_pin;                // digital input pin assigned to the switch
90  int  circuit_type;              // the type of circuit wired to the switch
91  bool switch_on_value;           // used for BUTTON SWITCHES only - defines what  "on" means, set up in setup()
92  bool switch_pending;            // records  if switch in transition or not
93  long unsigned int elapse_timer; // records debounce  timer count when associated switch is in transition
94  bool switch_status;             //  used for TOGGLE SWITCHES only - current state of toggle switch.
95} switches[num_switches]  = {
96  // Note order of preset entries not relevant, but keep in a tidy order
97
98  button_switch, button_switch_1, circuit_C1, LOW, false, 0, not_used,
99  button_switch,  button_switch_2, circuit_C2, LOW, false, 0, not_used,
100  button_switch, button_switch_3,  circuit_C1, LOW, false, 0, not_used,
101
102  toggle_switch, toggle_switch_1, circuit_C2,  not_used, false, 0, !on,
103  toggle_switch, toggle_switch_2, circuit_C1, not_used,  false, 0, !on,
104  toggle_switch, toggle_switch_3, circuit_C2, not_used, false,  0, !on
105
106};
107// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
108
109void  setup() {
110  // Initialise digital input switch pins
111  for (int sw = 0; sw  < num_switches; sw++) {
112    // Define the switch circuit type - circuit_type  is:
113    // circuit_C1 (INPUT) or circuit_C2 (INPUT_PULLUP)
114    pinMode(switches[sw].switch_pin,  switches[sw].circuit_type);
115    // Establish 'meaning' for switch on/off for  a button switch, depending on circuit type.
116    // This is used only by button  read function, it has no relevance for toggle switches.
117    if (switches[sw].circuit_type  == circuit_C2) {
118      // Switch is NOT configured with a pull down switch resistor
119      switches[sw].switch_on_value   = LOW;    // switch pin goes LOW when switch  pressed, ie on
120    } else {
121      // Circuit_type_C1, so switch IS configured  with a pull down switch resistor
122      switches[sw].switch_on_value   = HIGH;   // switch pin goes HIGH when switch pressed, ie on
123    }
124  }
125  Serial.begin(115200);  // dont forget to set your serial monitor speed to whatever is set here
126}  //  end of setup
127
128void loop() {
129  // Poll each connected switch in turn and,  if switched, process its associated purpose
130  for (int sw = 0; sw < num_switches;  sw++) {
131    if (read_switch(sw) == switched) {
132      // This switch (sw) has  been pressed, so process via a case switch
133      if (switches[sw].switch_type  == button_switch) {
134        Serial.print("\
135button switch on digital pin ");
136      } else {
137        Serial.print("\
138toggle switch on digital pin ");
139      }
140      Serial.print(switches[sw].switch_pin);
141      Serial.println("  triggered");
142      // Move to switch's associated code section
143
144      switch  (switches[sw].switch_pin)
145      {
146        case button_switch_1:
147          Serial.println("case  statement 1 entered");
148          break;
149        case button_switch_2:
150          Serial.println("case statement 2 entered");
151          break;
152        case button_switch_3:
153          Serial.println("case statement 3 entered");
154          break;
155        case toggle_switch_1:
156          Serial.println("case  statement 4 entered");
157          Serial.print("switch is ");
158          Serial.println(switches[sw].switch_status);
159          break;
160        case toggle_switch_2:
161          Serial.println("case  statement 5 entered");
162          Serial.print("switch is ");
163          Serial.println(switches[sw].switch_status);
164          break;
165        case toggle_switch_3:
166          Serial.println("case  statement 6 entered");
167          Serial.print("switch is ");
168          Serial.println(switches[sw].switch_status);
169          break;
170        default:
171          // Spurious switch index!  Should  never arise as this is controlled
172          // by the for loop within defined  upper bound
173          break;
174      }
175      Serial.flush();  // flush out  the output buffer
176    }
177  }
178  // Pollng of the switches now complete until  next cycle, so do other things here as required...
179
180
181
182} // end of main  loop
183
184// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
185// Generic  switch read function:
186// '''''''''''''''''''''''''''''
187// Read the switch  defined by the function parameter.
188// Function returns a value indicating if  the switch
189// has undergone a transition or not.
190// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
191bool  read_switch(int sw) {
192  if (switches[sw].switch_type == button_switch) {
193    return read_button_switch(sw);
194  }
195  return read_toggle_switch(sw);
196}  // end of read_switch
197
198// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
199//  Generic toggle switch read function:
200// '''''''''''''''''''''''''''''''''''
201//  Test the toggle switch to see if its status has changed since last look.
202// Note  that, although, switch status is a returned value from the function,
203// the current  status of the switch ('switches[sw].switch_status') is always
204// maintained and  can be tested outside of the function at any point/time.
205// It will either have  a switches[sw].switch_status of 'on' or '!on' (ie off).
206// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
207bool  read_toggle_switch(int sw) {
208  int pin_value = digitalRead(switches[sw].switch_pin);  // test current state of toggle pin
209  if (switches[sw].circuit_type == circuit_C2)  {
210    // Need to invert HIGH/LOW if circuit design sets pin HIGH representing  switch in off state
211    // ie inititialised as INPUT_PULLUP
212    pin_value  = !pin_value;
213  }
214  if (pin_value != switches[sw].switch_status && !switches[sw].switch_pending)  {
215    // Switch change detected so start debounce cycle
216    switches[sw].switch_pending  = true;
217    switches[sw].elapse_timer = millis();  // set start of debounce timer
218  } else {
219    if (switches[sw].switch_pending) {
220      // We are in the switch  transition cycle so check if debounce period has elapsed
221      if (millis() -  switches[sw].elapse_timer >= debounce) {
222        // Debounce period elapse so  assume switch has settled down after transition
223        switches[sw].switch_status  = !switches[sw].switch_status;  // flip status
224        switches[sw].switch_pending  = false;                       // cease transition cycle
225        return switched;
226      }
227    }
228  }
229  return !switched;
230} // end of read_toggle_switch
231
232//  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
233// Read button switch  function:
234// ''''''''''''''''''''''''''''
235// Generic button switch read function.
236//  Reading is controlled by:
237//   a. the function parameter which indicates which  switch
238//      is to be polled, and
239//   b. the switch control struct(ure),  referenced by a).
240//
241// Note that this function works in a nonexclusive way
242//  and incorporates debounce code.
243// %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
244
245bool  read_button_switch(int sw) {
246  int switch_pin_reading;
247  switch_pin_reading  = digitalRead(switches[sw].switch_pin);
248  if (switch_pin_reading == switches[sw].switch_on_value)  {
249    // Switch is pressed (ON), so start/restart debounce process
250    switches[sw].switch_pending  = true;
251    switches[sw].elapse_timer = millis();    // start elapse timing
252    return !switched;                        // now waiting for debounce to conclude
253  }
254  if (switches[sw].switch_pending && switch_pin_reading == !switches[sw].switch_on_value)  {
255    // Switch was pressed, now released (OFF), so check if debounce time elapsed
256    if (millis() - switches[sw].elapse_timer > debounce) {
257      // dounce time  elapsed, so switch press cycle complete
258      switches[sw].switch_pending = false;
259      return switched;
260    }
261  }
262  return !switched;
263}  // end of read_button_switch
264