SparkFunDMX: fix for issue wled#2928

* make SparlFunDMX driver more robust:
- made variables static (so they don't overlap with other global variables)
- made sure all valriables are properly initialized
- do not apply pinMode and digitalRead to invalid pins (as this creates problems on -S3, -C3 and -S2)
* disable DMX sending code (unneeded code that may case troubles)

Author: softhack007

wled00/src/dependencies/dmx/SparkFunDMX.cpp

@@ -14,7 +14,7 @@ Distributed as-is; no warranty is given.
 ******************************************************************************/
 
 /* ----- LIBRARIES ----- */
-#ifdef ESP32
+#ifdef ARDUINO_ARCH_ESP32
 
 #include <Arduino.h>
 
@@ -29,28 +29,36 @@ Distributed as-is; no warranty is given.
 #define BREAKSPEED     83333
 #define BREAKFORMAT    SERIAL_8N1
 
-int enablePin = -1;		// disable the enable pin because it is not needed
-int rxPin = -1;       // disable the receiving pin because it is not needed
-int txPin = 2;        // transmit DMX data over this pin (default is pin 2)
+static const int enablePin = -1;		// disable the enable pin because it is not needed
+static const int rxPin = -1;       // disable the receiving pin because it is not needed - softhack007: Pin=-1 means "use default" not "disable"
+static const int txPin = 2;        // transmit DMX data over this pin (default is pin 2)
 
 //DMX value array and size. Entry 0 will hold startbyte
-uint8_t dmxData[dmxMaxChannel] = {};
-int chanSize;
-int currentChannel = 0;
+static uint8_t dmxData[dmxMaxChannel] = { 0 };
+static int chanSize = 0;
+static int currentChannel = 0;
 
-HardwareSerial DMXSerial(2);
+// Some new MCUs (-S2, -C3) don't have HardwareSerial(2)
+#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 2, 0)
+  #if SOC_UART_NUM < 3
+  #error DMX output is not possible on your MCU, as it not have HardwareSerial(2)
+  #endif
+#endif
+
+static HardwareSerial DMXSerial(2);
 
 /* Interrupt Timer for DMX Receive */
-hw_timer_t * timer = NULL;
-portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;
+static hw_timer_t * timer = NULL;
+static portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;
 
-volatile int _interruptCounter;
-volatile bool _startCodeDetected = false;
+static volatile int _interruptCounter = 0;
+static volatile bool _startCodeDetected = false;
 
 
+#if !defined(DMX_SEND_ONLY)
 /* Start Code is detected by 21 low interrupts */
 void IRAM_ATTR onTimer() {
-	if (digitalRead(rxPin) == 1)
+	if ((rxPin >= 0) && (digitalRead(rxPin) == 1))
 	{
 		_interruptCounter = 0; //If the RX Pin is high, we are not in an interrupt
 	}
@@ -80,10 +88,13 @@ void SparkFunDMX::initRead(int chanQuant) {
     chanQuant = defaultMax;
   }
   chanSize = chanQuant;
-  pinMode(enablePin, OUTPUT);
-  digitalWrite(enablePin, LOW);
-  pinMode(rxPin, INPUT);
+  if (enablePin >= 0) {
+    pinMode(enablePin, OUTPUT);
+    digitalWrite(enablePin, LOW);
+  }
+  if (rxPin >= 0) pinMode(rxPin, INPUT);
 }
+#endif
 
 // Set up the DMX-Protocol
 void SparkFunDMX::initWrite (int chanQuant) {
@@ -96,15 +107,19 @@ void SparkFunDMX::initWrite (int chanQuant) {
   chanSize = chanQuant + 1; //Add 1 for start code
 
   DMXSerial.begin(DMXSPEED, DMXFORMAT, rxPin, txPin);
-  pinMode(enablePin, OUTPUT);
-  digitalWrite(enablePin, HIGH);
+  if (enablePin >= 0) {
+    pinMode(enablePin, OUTPUT);
+    digitalWrite(enablePin, HIGH);
+  }
 }
 
+#if !defined(DMX_SEND_ONLY)
 // Function to read DMX data
 uint8_t SparkFunDMX::read(int Channel) {
   if (Channel > chanSize) Channel = chanSize;
   return(dmxData[Channel - 1]); //subtract one to account for start byte
 }
+#endif
 
 // Function to send DMX data
 void SparkFunDMX::write(int Channel, uint8_t value) {
@@ -133,6 +148,7 @@ void SparkFunDMX::update() {
     DMXSerial.flush();
     DMXSerial.end();//clear our DMX array, end the Hardware Serial port
   }
+#if !defined(DMX_SEND_ONLY)
   else if (_READWRITE == _READ)//In a perfect world, this function ends serial communication upon packet completion and attaches RX to a CHANGE interrupt so the start code can be read again
   { 
 	if (_startCodeDetected == true)
@@ -153,6 +169,7 @@ void SparkFunDMX::update() {
 	}
 	}
   }
+#endif
 }
 
 // Function to update the DMX bus

wled00/src/dependencies/dmx/SparkFunDMX.h

@@ -19,19 +19,23 @@ Distributed as-is; no warranty is given.
 #ifndef SparkFunDMX_h
 #define SparkFunDMX_h
 
+#define DMX_SEND_ONLY // this disables DMX sending features, and saves us two GPIO pins
+
 // ---- Methods ----
 
 class SparkFunDMX {
 public:
-  void initRead(int maxChan);
   void initWrite(int maxChan);
+  #if !defined(DMX_SEND_ONLY)
+  void initRead(int maxChan);
   uint8_t read(int Channel);
+  #endif
   void write(int channel, uint8_t value);
   void update();
 private:
-  uint8_t _startCodeValue = 0xFF;
-  bool _READ = true;
-  bool _WRITE = false;
+  const uint8_t _startCodeValue = 0xFF;
+  const bool _READ = true;
+  const bool _WRITE = false;
   bool _READWRITE;
 };