receive non blocking, using optional timeout

examples/DmxSerialNeoPixels/DmxSerialNeoPixels.ino

@@ -66,16 +66,22 @@ void setup () {
 // do constantly fetch DMX data and update the neopixels.
 void loop() {
   // wait for an incomming DMX packet.
-  DMXSerial.receive();
-
-  // read recent DMX values 1..3 and set pwm levels
-  analogWrite(RedPin,   DMXSerial.read(1));
-  analogWrite(GreenPin, DMXSerial.read(2));
-  analogWrite(BluePin,  DMXSerial.read(3));
+  if (DMXSerial.receive()) {
+    analogWrite(RedPin,   DMXSerial.read(1));
+    analogWrite(GreenPin, DMXSerial.read(2));
+    analogWrite(BluePin,  DMXSerial.read(3));
+    updateNeopixel(DMXSerial.getBuffer() + DMXSTART, PIXELS);
+
+  } else {
+    // don't update the Neopixels but signal a red.
+    analogWrite(RedPin,   100);
+    analogWrite(GreenPin, 0);
+    analogWrite(BluePin,  0);
+  } // if
 
-  updateNeopixel(DMXSerial.getBuffer() + DMXSTART, PIXELS);
 } // loop()
 
+
 // The End.
 
 

src/DMXSerial.cpp

@@ -353,22 +353,37 @@ void DMXSerialClass::resetUpdated()
 
 
 // When mode is DMXProbe this function reads one DMX buffer and then returns.
-void DMXSerialClass::receive()
+// wait a meaningful time on a packet.
+// return true whan a packet has been received.
+bool DMXSerialClass::receive() {
+  return(receive(DMXPROBE_RECV_MAX));
+} // receive()
+
+
+// When mode is DMXProbe this function reads one DMX buffer and then returns.
+// wait approximately gives the number of msecs for waiting on a packet.
+// return true whan a packet has been received.
+bool DMXSerialClass::receive(uint8_t wait)
 {
+  bool ret = false;
+
   if (_dmxMode == DMXProbe) {
     _DMXStartReceiving();
      // UCSRnA
-    while (_dmxRecvState != DONE) {
-      delay(5);
+    while ((wait > 0) && (_dmxRecvState != DONE)) {
+      delay(1);
+      wait--;
     } // while
 
-    if ((_dmxData[1] == 0) && (_dmxData[2] == 0)) {
-      // digitalWrite(9, 1);
-      // delay(500);
-      // digitalWrite(9, 0);
-    }
+    if (_dmxRecvState == DONE) {
+      ret = true;
+    } else {
+      _DMXSerialInit(Calcprescale(DMXSPEED), (1 << RXENn), DMXFORMAT);
+    } // if
   } // if
-} // receive()
+
+  return(ret);
+} // receive(wait)
 
 
 // Terminate operation

src/DMXSerial.h

@@ -31,6 +31,8 @@
 #define DmxModeOut HIGH  // set the level to HIGH for outgoing data direction
 #define DmxModeIn  LOW   // set the level to LOW  for incomming data direction
 
+#define DMXPROBE_RECV_MAX 50 // standard maximum of waiting for a DMX packet in DMXPROBE mode.
+
 // ----- Enumerations -----
 
 // Mode of Operation
@@ -77,8 +79,11 @@ class DMXSerialClass
     void resetUpdated();
 
     // actively wait for an incomming DMX packet.
-    void receive();
+    bool receive();
 
+    // actively wait for an incomming DMX packet, specifying the maximal waiting time in msecs.
+    bool receive(uint8_t wait);
+
     // Terminate operation.
     void    term       (void);