Rotary switch for Arduino Nano with Debouncing, Maximum Range, Value Lock, and Position Memory

rotary_switch.ino

struct signal {
  byte curr;
  byte prev;
};

struct signalDb {
  byte curr;
  byte prev;
  signal db;
};

#define sigFetch(sig, pin) \
  (sig).curr = digitalRead (pin);
  
#define sigTick(sig) \
  (sig).prev = (sig).curr
  
#define sigInit(sig, pin) \
  sigFetch ((sig), (pin));
  
#define sigPump(sig, pin) \
  sigTick (sig); \
  sigFetch ((sig), (pin));
  
#define sigChanged(sig) ((sig).curr != (sig).prev)
  
#define sigRaised(sig) ((sig).curr == HIGH && (sig).prev == LOW)

#define sigDbFetch(sig, pin) \
  (sig).db.curr = ((sig).db.curr << 1) | digitalRead (pin); \
  if (!((sig).db.prev ^ (sig).db.curr)) { \
    (sig).curr = (sig).db.curr & 0x1; \
  }
  
#define sigDbInit(sig, pin) \
  sigFetch ((sig), (pin)); \
  (sig).db.curr = (sig).curr ? 0xFF : 0;
  
#define sigDbPump(sig, pin) \
  sigTick (sig); \
  sigTick ((sig).db); \
  sigDbFetch ((sig), (pin));

struct rotary {
  signal sw;
  signal clk;
  signalDb dt;
};

#define rotInit(rot, SW, CLK, DT) \
  pinMode (SW, INPUT);
  pinMode (CLK, INPUT);
  pinMode (DT, INPUT);
  sigInit ((rot).sw, SW); \
  sigInit ((rot).clk, CLK); \
  sigDbInit ((rot).dt, DT);

#define rotPump(rot, SW, CLK, DT) \
  sigPump ((rot).sw, SW); \
  sigPump ((rot).clk, CLK); \
  sigDbPump ((rot).dt, DT);

#define rotChanged(rot) (sigChanged (rot.dt) && (rot).clk.curr == HIGH)

#define rotCw(rot) ((rot).dt.curr != (rot).clk.curr)

#define SW0  2
#define CLK0 3
#define DT0  4

#define SW1  5
#define CLK1 6
#define DT1  7

rotary rCtrl;
rotary rVal;

byte ctrl;
int pos;
int bias[256];

boolean ctrlLock;
boolean valLock;

void setup ()
{
  rotInit (rCtrl, SW0, CLK0, DT0);
  rotInit (rVal, SW1, CLK1, DT1);

  Serial.begin (9600);
}

void loop ()
{
  delayMicroseconds (500);

  rotPump (rCtrl, SW0, CLK0, DT0);
  rotPump (rVal, SW1, CLK1, DT1);
  
  if (!ctrlLock && rotChanged (rCtrl)) {
    bias[ctrl] = pos;
    if (rotCw (rCtrl))
      ctrl++;
    else
      ctrl--;
    pos = bias[ctrl];
    
    Serial.print ("Control ");
    Serial.print (ctrl);
    Serial.print (": ");
    Serial.println (pos);
  }
  
  if (sigRaised (rCtrl.sw)) {
    ctrlLock = !ctrlLock;
    Serial.print ("LOCKED: Control: ");
    Serial.println (ctrlLock);
  }
  
  if (!valLock && rotChanged (rVal)) {
    if (rotCw (rVal))
      pos++;
    else
      pos--;
    
    Serial.print ("Control");
    Serial.print (ctrl);
    Serial.print (": ");
    Serial.println (pos);
  }
  
  if (sigRaised (rVal.sw)) {
    valLock = !valLock;
    Serial.print ("LOCKED: Value: ");
    Serial.println (valLock);
  }
}