Add an aditional (void *) arg to the RMT callback (much like Ticker() et.al.). (#3345)

* Add an aditional (void *) arg to the RMT callback - to allow more flexible handling of the callback (e.g. by passing a private struct or a class pointer). Same pattern as used by the Ticker() and many others. Example updated & new example with a trapoline added.

* Fix example for new API

* Fix lint warnings

* Add a second missed example.

* Correct timeout & improve socket error handling.

libraries/ESP32/examples/RMT/RMTCallback/RMTCallback.ino

@@ -0,0 +1,64 @@
+#include "Arduino.h"
+#include "esp32-hal.h"
+
+extern "C" void receive_trampoline(uint32_t *data, size_t len, void * arg);
+
+class MyProcessor {
+  private:
+    rmt_obj_t* rmt_recv = NULL;
+    float realNanoTick;
+    uint32_t buff; // rolling buffer of most recent 32 bits.
+    int at = 0;
+
+  public:
+    MyProcessor(uint8_t pin, float nanoTicks) {
+      assert((rmt_recv = rmtInit(21, false, RMT_MEM_192)));
+
+      realNanoTick = rmtSetTick(rmt_recv, nanoTicks);
+    };
+    void begin() {
+      rmtRead(rmt_recv, receive_trampoline, this);
+    };
+
+    void process(rmt_data_t *data, size_t len) {
+      for (int i = 0; len; len--) {
+        if (data[i].duration0 == 0)
+          break;
+        buff = (buff << 1) | (data[i].level0 ? 1 : 0);
+        i++;
+
+        if (data[i].duration1 == 0)
+          break;
+        buff = (buff << 1) | (data[i].level1 ? 1 : 0);
+        i++;
+      };
+    };
+    uint32_t val() {
+      return buff;
+    }
+};
+
+void receive_trampoline(uint32_t *data, size_t len, void * arg)
+{
+  MyProcessor * p = (MyProcessor *)arg;
+  p->process((rmt_data_t*) data, len);
+}
+
+// Attach 3 processors to GPIO 4, 5 and 10 with different tick/speeds.
+MyProcessor mp1 = MyProcessor(4, 1000);
+MyProcessor mp2 = MyProcessor(5, 1000);
+MyProcessor mp3 = MyProcessor(10, 500);
+
+void setup()
+{
+  Serial.begin(115200);
+  mp1.begin();
+  mp2.begin();
+  mp3.begin();
+}
+
+void loop()
+{
+  Serial.printf("GPIO 4: %08x 5: %08x 6: %08x\n", mp1.val(), mp2.val(), mp3.val());
+  delay(500);
+}

libraries/ESP32/examples/RMT/RMTReadXJT/RMTReadXJT.ino

@@ -172,7 +172,7 @@ void parseRmt(rmt_data_t* items, size_t len, uint32_t* channels){
     }
 }
 
-extern "C" void receive_data(uint32_t *data, size_t len)
+extern "C" void receive_data(uint32_t *data, size_t len, void * arg)
 {
     parseRmt((rmt_data_t*) data, len, channels);
 }
@@ -192,7 +192,7 @@ void setup()
     Serial.printf("real tick set to: %fns\n", realTick);
 
     // Ask to start reading
-    rmtRead(rmt_recv, receive_data);
+    rmtRead(rmt_recv, receive_data, NULL);
 }
 
 void loop()