One more ISR improvement

tasmota/xdrv_47_ftc532.ino

@@ -49,13 +49,41 @@
 
   Timing of an ALL OFF frame in clock cycles T=377µs, triggering on rising edge:
   IDLE-2222444422224444-IDLE
+  
+  *********************
+  * About this driver *
+  *********************
+  
+  This driver implements the reverse engineered protocol of the FTC532 touch controller.
+  The protocol encodes the bitmap of touched keys in variable length pulses comprising a
+  fixed length frame. These frames are then sent out continuously from the FTC532 chip.
+  The first version of this driver was working fine on well behaved hardware. After being
+  released to the field and installed on crappy hardware in noisy environments it developed
+  a habit of random 'ghost' switchings at night, much to the chagrin of some users.
+  This is almost a re-write containing a lot more timing (and other) checks in order to
+  detect and mitigate various incarnations of noise.
+  If you should still experience 'ghost switching' issues a solution may be increasing
+  FTC532_DEBOUNCE to 2 or higher. That will enable the de-bouncing code, at the expense of
+  'snappiness' of touch reactions. Higher values will accumulate more samples in 50 ms steps
+  before actually firing the rules trigger. It will eat a few bytes off your RAM and Flash
+  budget, too.
+  
+  Usage:
+  ------
+  This driver does not actually switch anything. It is a pure "rules" driver that solely emits
+  {"FTC532":{"KEYS":"XX"}} JSON messages to be used in a rule or by an MQTT broker. "XX" stands
+  for the hexadecimal (big endian) representation of a bitmap of keys currently touched, where
+  e.g. "00" means "no key touched" while "03" means "keys 1 and 2 touched simultaneously".
+  Selecting "FTC532" on a GPIO will awake the driver. This driver can only be selected once.
+
+  
 \*********************************************************************************************/
 
 #define XDRV_47                   47
 
+#define FTC532_DEBOUNCE           0     // no. of cycles, < 2 disables the code
 #define FTC532_KEYS               4     // number of key pins on chip
 #define FTC532_KEYS_MAX           8     // number of key slots in protocol
-#define FTC532_DEBOUNCE           0     // number of consecutive cycles until key accepted
 
 #define FTC532_STATE_WAITING      0x1
 #define FTC532_STATE_READING      0x2
@@ -79,15 +107,15 @@ struct FTC532 {
   volatile uint16_t state;              // ISR state
   uint8_t keys              = 0;        // bitmap of active keys
   uint8_t old_keys          = 0;        // previously active keys
+  bool present              = false;    // driver active
 #if FTC532_DEBOUNCE > 1
   uint8_t key_cnt           = 0;        // used to de-bounce
 #endif  // FTC532_DEBOUNCE > 1
-  bool present = false;                 // driver active
 #ifdef DEBUG_FTC532
-  volatile uint16_t e_inv   = 0;        // inv. key error counter
+  volatile uint16_t e_inv   = 0;        // inverted key error counter
   volatile uint16_t e_frame = 0;        // frame error counter
   volatile uint16_t e_noise = 0;        // noise detection counter
-  volatile bool valid = 0;              // did we ever receive valid data?
+  volatile bool valid       = 0;        // did we ever receive valid data?
 #endif  // DEBUG_FTC532
 } Ftc532;
 
@@ -108,37 +136,36 @@ void ICACHE_RAM_ATTR ftc532_ISR(void) {   // Hardware interrupt routine, trigger
 #endif  // DEBUG_FTC532
       }
       Ftc532.state = FTC532_STATE_READING;
+      Ftc532.tsmp = 0;
     } else {
       Ftc532.state = FTC532_STATE_WAITING;
     }
     return;
   }
-        // FTC532_STATE_READING starts here
+  // FTC532_STATE_READING starts here
   if (time_diff > FTC532_LONG + FTC532_BIT) {
 #ifdef DEBUG_FTC532
-    ++Ftc532.e_frame;                             // frame error
+    ++Ftc532.e_frame;                               // frame error
 #endif  // DEBUG_FTC532
     Ftc532.state = FTC532_STATE_WAITING;
     return;
   }
   if (time_diff > FTC532_SHORT + FTC532_BIT) {
-    Ftc532.tsmp |= (1 << Ftc532.rxbit);           // LONG
+    Ftc532.tsmp |= (1 << Ftc532.rxbit);             // LONG
-  } else if (time_diff < FTC532_NOISE) {          // noise detector
+  } else if (time_diff < FTC532_NOISE) {            // NOISE
 #ifdef DEBUG_FTC532
     ++Ftc532.e_noise;
 #endif  // DEBUG_FTC532
     Ftc532.state = FTC532_STATE_WAITING;
     return;
-  } else {
-    Ftc532.tsmp &= ~(1 << Ftc532.rxbit);          // SHORT
   }
   ++Ftc532.rxbit;
-  if (Ftc532.rxbit == FTC532_KEYS_MAX * 2) {      // frame complete
+  if (Ftc532.rxbit == FTC532_KEYS_MAX * 2) {        // frame complete
     Ftc532.state = FTC532_STATE_COMPLETE;
   }
 }
 
-void ftc532_init(void) {                          // Initialize
+void ftc532_init(void) {                            // Initialize
   if (!PinUsed(GPIO_FTC532)) { return; }
   Ftc532.state = FTC532_STATE_WAITING;
   pinMode(Pin(GPIO_FTC532), INPUT_PULLUP);
@@ -147,7 +174,7 @@ void ftc532_init(void) {                          // Initialize
   Ftc532.present = true;
 }
 
-void ftc532_update(void) {                        // Usually called every 50 ms
+void ftc532_update(void) {                          // Usually called every 50 ms
   if ((Ftc532.sample & 0xF0F0) == ((~Ftc532.sample & 0x0F0F) << 4) && (Ftc532.sample >> 8) == 0xF0) {
     Ftc532.keys = Ftc532.sample & 0xF;
     if (Ftc532.keys != Ftc532.old_keys) {
@@ -156,7 +183,8 @@ void ftc532_update(void) {                        // Usually called every 50 ms
 #endif  // FTC532_DEBOUNCE > 1
 #ifdef DEBUG_FTC532
         AddLog_P(LOG_LEVEL_DEBUG, PSTR("FTC: SAM=%04X KEY=%X OLD=%X INV=%u NOI=%u FRM=%u OK=%u TIME=%lu Pin=%u"),
-                Ftc532.sample, Ftc532.keys, Ftc532.old_keys, Ftc532.e_inv, Ftc532.e_noise, Ftc532.e_frame, Ftc532.valid, Ftc532.rxtime, Pin(GPIO_FTC532));
+                 Ftc532.sample, Ftc532.keys, Ftc532.old_keys, Ftc532.e_inv, Ftc532.e_noise, Ftc532.e_frame,
+                 Ftc532.valid, Ftc532.rxtime, Pin(GPIO_FTC532));
 #endif  // DEBUG_FTC532
         ftc532_publish();
         Ftc532.old_keys = Ftc532.keys;
@@ -171,7 +199,7 @@ void ftc532_update(void) {                        // Usually called every 50 ms
 #ifdef DEBUG_FTC532
   else {
     ++Ftc532.e_inv;
-    AddLog_P(LOG_LEVEL_DEBUG, PSTR("FTC: SAM=%04X"), Ftc532.sample);
+    AddLog_P(LOG_LEVEL_DEBUG, PSTR("FTC: ILL SAM=%04X"), Ftc532.sample);
   }
 #endif  // DEBUG_FTC532
 }