adding a simple example

Author: david-cermak

Diff for: cores/esp32/esp32-hal-rmt.h

@@ -1,4 +1,3 @@
-
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -19,17 +18,42 @@ typedef struct rmt_obj_s rmt_obj_t;
 */
 rmt_obj_t* rmtInit(int pin, bool tx_not_rx, int entries, int period);
 
+/**
+*    Sets the clock/divider of timebase the nearest tick to the supplied value in nanoseconds
+*    return the real actual tick value in ns
+*/
 float rmtSetTick(rmt_obj_t* rmt, float tick);
 
+/**
+*    Sending data in one-go mode (more data must span over multiple channels)
+*
+*/
 bool rmtSend(rmt_obj_t* rmt, uint32_t* data, size_t size);
 
+/**
+*    Sending data in one-go mode (more data being send while updating buffers in interrupts)
+*
+*/
 bool rmtSendQueued(rmt_obj_t* rmt, uint32_t* data, size_t size);
 
+/**
+*    Initiates simple data receive without interrupts
+*
+*/
 bool rmtReceive(rmt_obj_t* rmt, size_t idle_thres);
 
+/**
+*    Wait method for synchronous receive
+*
+*/
+bool rmtWaitForData(rmt_obj_t* rmt, uint32_t* data, size_t size);
+
+/**
+*    Initiates async receive, event flag indicates data received
+*
+*/
 bool rmtReceiveAsync(rmt_obj_t* rmt, size_t idle_thres, uint32_t* data, size_t size, void* event_flags);
 
-bool rmtWaitForData(rmt_obj_t* rmt, uint32_t* data, size_t size);
 
 
 // TODO:

Diff for: libraries/ESP32/examples/RMTLoopback/RMTLoopbakc.ino

@@ -0,0 +1,63 @@
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "Arduino.h"
+
+#include "esp32-hal-rmt.h"
+
+uint32_t my_data[256];
+
+uint32_t data[256];
+
+rmt_obj_t* rmt_send = NULL;
+rmt_obj_t* rmt_recv = NULL;
+
+
+void setup() 
+{
+    if ((rmt_send = rmtInit(18, true, 2, 1000)) == NULL)
+    {
+        printf("init sender failed\n");
+    }
+    if ((rmt_recv = rmtInit(21, false, 2, 1000)) == NULL)
+    {
+        printf("init receiver failed\n");
+    }
+
+
+    float realTick = rmtSetTick(rmt_send, 400);
+    printf("real tick set to: %f\n", realTick);
+    realTick = rmtSetTick(rmt_recv, 400);
+    printf("real tick set to: %f\n", realTick);
+
+    events = xEventGroupCreate();
+}
+
+void loop() 
+{
+    // Init data
+    int i;
+    for (i=0; i<255; i++) {
+        data[i] = 0x80010001 + ((i%13)<<16) + 13-(i%13);
+    }
+    data[255] = 0;
+
+    // Start receiving
+    rmtReceiveAsync(rmt_recv, 0x4F, my_data, 60, events);
+
+    // Send in continous mode
+    rmtSendQueued(rmt_send, data, 56);
+
+    // Wait for data
+    xEventGroupWaitBits(events, RMT_FLAG_RX_DONE, 1, 1, portMAX_DELAY);
+
+    // Printout the received data plus the original values
+    for (i=0; i<60; i++)
+    {
+        printf("%08x=%08x ", my_data[i], data[i] );
+        if (!((i+1)%4)) printf("\n");
+    }
+    printf("\n");
+
+    delay(2000);
+}