add support for nexus protocol to rc-switch library (#21886)

* add support for nexus protocol to RCSwitch library

Nexus protocol is used by temperature and humidity sensor that operate at 433 MHz.
It is used by various brands.

* calc separation limit for RCSwitch library automatically

lib/lib_rf/rc-switch/src/RCSwitch.cpp

@@ -151,8 +151,9 @@ static const RCSwitch::Protocol PROGMEM proto[] = {
   { 340,  0, { 0, 0 }, 1, {  14,  4 }, { 1,  2 }, { 2, 1 }, false,  0 },  // 33 (Dooya Control DC2708L)
   { 120,  0, { 0, 0 }, 1, {   1, 28 }, { 1,  3 }, { 3, 1 }, false,  0 },  // 34 DIGOO SD10 - so as to use this protocol RCSWITCH_SEPARATION_LIMIT must be set to 2600
   { 20,   0, { 0, 0 }, 1, { 239, 78 }, {20, 35 }, {35, 20}, false, 10000},// 35 Dooya 5-Channel blinds remote DC1603
-  { 250,  0, { 0, 0 }, 1, {  18,  6 }, { 1,  3 }, { 3, 1 }, false,  0 },   // 36 Dooya remote DC2700AC for Dooya DT82TV curtains motor
+  { 250,  0, { 0, 0 }, 1, {  18,  6 }, { 1,  3 }, { 3, 1 }, false,  0 },  // 36 Dooya remote DC2700AC for Dooya DT82TV curtains motor
-  { 200,  0, { 0, 0 }, 0, {   0,  0 }, { 1,  3 }, { 3, 1} , false, 20}	  // 37 DEWENWILS Power Strip
+  { 200,  0, { 0, 0 }, 0, {   0,  0 }, { 1,  3 }, { 3, 1 }, false, 20 },	// 37 DEWENWILS Power Strip
+  { 500,  0, { 0, 0 }, 1, {   7,  1 }, { 2,  1 }, { 4, 1 }, true,   0 },  // 38 temperature and humidity sensor, various brands, nexus protocol, 36 bits + start impulse  
 };
 
 enum {
@@ -166,7 +167,7 @@ volatile unsigned int RCSwitch::nReceivedBitlength = 0;
 volatile unsigned int RCSwitch::nReceivedDelay = 0;
 volatile unsigned int RCSwitch::nReceivedProtocol = 0;
 int RCSwitch::nReceiveTolerance = 60;
-const unsigned int RCSwitch::nSeparationLimit = RCSWITCH_SEPARATION_LIMIT;
+unsigned int RCSwitch::nSeparationLimit = RCSWITCH_SEPARATION_LIMIT;
 unsigned int RCSwitch::timings[RCSWITCH_MAX_CHANGES];
 unsigned int RCSwitch::buftimings[4];
 #endif
@@ -238,8 +239,50 @@ void RCSwitch::setReceiveTolerance(int nPercent) {
   RCSwitch::nReceiveTolerance = nPercent;
 }
 
-void RCSwitch::setReceiveProtocolMask(unsigned long long mask) {
+bool RCSwitch::setReceiveProtocolMask(unsigned long long mask) {
   RCSwitch::nReceiveProtocolMask = mask;
+  return updateSeparationLimit();
+}
+
+bool RCSwitch::updateSeparationLimit()
+{
+  unsigned int longestPulseTime = std::numeric_limits<unsigned int>::max();
+  unsigned int shortestPulseTime = 0;
+
+  unsigned long long thisMask = 1;
+  for(unsigned int i = 0; i < numProto; i++) {
+    if (RCSwitch::nReceiveProtocolMask & thisMask) {
+      const unsigned int headerShortPulseCount = std::min(proto[i].Header.high, proto[i].Header.low);
+      const unsigned int headerLongPulseCount = std::max(proto[i].Header.high, proto[i].Header.low);
+
+      // This must be the longest pulse-length of this protocol. nSeparationLimit must of this length or shorter.
+      // This pulse will be used to detect the beginning of a transmission.
+      const unsigned int headerLongPulseTime = proto[i].pulseLength * headerLongPulseCount;
+
+      // nSeparationLimit must be longer than any of the following pulses to avoid detecting a new transmission in the middle of a frame.
+      unsigned int longestDataPulseCount = headerShortPulseCount;
+      longestDataPulseCount = std::max<unsigned int>(longestDataPulseCount, proto[i].zero.high);
+      longestDataPulseCount = std::max<unsigned int>(longestDataPulseCount, proto[i].zero.low);
+      longestDataPulseCount = std::max<unsigned int>(longestDataPulseCount, proto[i].one.high);
+      longestDataPulseCount = std::max<unsigned int>(longestDataPulseCount, proto[i].one.low);
+
+      const unsigned int longestDataPulseTime = proto[i].pulseLength * longestDataPulseCount;
+
+      longestPulseTime = std::min(longestPulseTime, headerLongPulseTime);
+      shortestPulseTime = std::max(shortestPulseTime, longestDataPulseTime);
+    }
+    thisMask <<= 1;
+  }
+
+  if (longestPulseTime <= shortestPulseTime) {
+    // incompatible protocols enabled, fall back to default value
+    nSeparationLimit = RCSWITCH_SEPARATION_LIMIT;
+    return false;
+  }
+
+  const unsigned int timeDiff = longestPulseTime - shortestPulseTime;
+  nSeparationLimit = longestPulseTime - (timeDiff / 2);
+  return true;
 }
 #endif
 

lib/lib_rf/rc-switch/src/RCSwitch.h

@@ -57,9 +57,9 @@
 #endif
 
 // Number of maximum high/Low changes per packet.
-// We can handle up to (unsigned long) => 32 bit * 2 H/L changes per bit + 2 for sync
+// We can handle up to 36 bit * 2 H/L changes per bit + 2 for sync
 // Для keeloq нужно увеличить RCSWITCH_MAX_CHANGES до 23+1+66*2+1=157
-#define RCSWITCH_MAX_CHANGES 67        // default 67
+#define RCSWITCH_MAX_CHANGES 75        // default 75 - longest protocol that requires this buffer size is 38/nexus
 
 // separationLimit: minimum microseconds between received codes, closer codes are ignored.
 // according to discussion on issue #14 it might be more suitable to set the separation
@@ -108,7 +108,7 @@ class RCSwitch {
     void setRepeatTransmit(int nRepeatTransmit);
     #if not defined( RCSwitchDisableReceiving )
     void setReceiveTolerance(int nPercent);
-    void setReceiveProtocolMask(unsigned long long mask);
+    bool setReceiveProtocolMask(unsigned long long mask);
     #endif
 
     /**
@@ -171,6 +171,7 @@ class RCSwitch {
     #if not defined( RCSwitchDisableReceiving )
     static void handleInterrupt();
     static bool receiveProtocol(const int p, unsigned int changeCount);
+    static bool updateSeparationLimit();
     int nReceiverInterrupt;
     #endif
     int nTransmitterPin;
@@ -184,7 +185,7 @@ class RCSwitch {
     volatile static unsigned int nReceivedBitlength;
     volatile static unsigned int nReceivedDelay;
     volatile static unsigned int nReceivedProtocol;
-    const static unsigned int nSeparationLimit;
+    static unsigned int nSeparationLimit;
     /*
      * timings[0] contains sync timing, followed by a number of bits
      */

tasmota/tasmota_xdrv_driver/xdrv_17_rcswitch.ino

@@ -92,7 +92,7 @@ void RfInit(void) {
     if (!Settings->rf_protocol_mask) {
       Settings->rf_protocol_mask = (1ULL << mySwitch.getNumProtos()) -1;
     }
-    mySwitch.setReceiveProtocolMask(Settings->rf_protocol_mask);
+    (void)mySwitch.setReceiveProtocolMask(Settings->rf_protocol_mask);
   }
 }
 
@@ -132,7 +132,10 @@ void CmndRfProtocol(void) {
       }
     }
   }
-  mySwitch.setReceiveProtocolMask(Settings->rf_protocol_mask);
+  const bool incompatibleProtocolsSelected = !mySwitch.setReceiveProtocolMask(Settings->rf_protocol_mask);
+  if (incompatibleProtocolsSelected) {
+    AddLog(LOG_LEVEL_INFO, PSTR("RFR: CmndRfProtocol:: Incompatible protocols selected, using default separation limit, some protocols may not work"));
+  }
 //  AddLog(LOG_LEVEL_INFO, PSTR("RFR: CmndRfProtocol:: Start responce"));
   Response_P(PSTR("{\"" D_CMND_RFPROTOCOL "\":\""));
   bool gotone = false;