refactor(rmt): refactored RMT loopback example (#11221)

* feat(rmt): refactored RMT loopback example

* ci(pre-commit): Apply automatic fixes

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: SuGlider

libraries/ESP32/examples/RMT/RMTLoopback/RMTLoopback.ino

@@ -1,4 +1,4 @@
-// Copyright 2023 Espressif Systems (Shanghai) PTE LTD
+// Copyright 2025 Espressif Systems (Shanghai) PTE LTD
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -35,40 +35,53 @@
 rmt_data_t my_data[256];
 rmt_data_t data[256];
 
-static EventGroupHandle_t events;
-
 #define RMT_FREQ               10000000  // tick time is 100ns
-#define RMT_NUM_EXCHANGED_DATA 30
+#define RMT_NUM_EXCHANGED_DATA 32
 
 void setup() {
   Serial.begin(115200);
-  events = xEventGroupCreate();
 
   if (!rmtInit(RMT_TX_PIN, RMT_TX_MODE, RMT_MEM_NUM_BLOCKS_1, RMT_FREQ)) {
     Serial.println("init sender failed\n");
   }
   if (!rmtInit(RMT_RX_PIN, RMT_RX_MODE, RMT_MEM_RX, RMT_FREQ)) {
     Serial.println("init receiver failed\n");
   }
+  Serial.println();
+  Serial.println("RMT tick set to: 100ns");
 
   // End of transmission shall be detected when line is idle for 2us = 20*100ns
   rmtSetRxMaxThreshold(RMT_RX_PIN, 20);
   // Disable Glitch  filter
   rmtSetRxMinThreshold(RMT_RX_PIN, 0);
 
-  Serial.println("real tick set to: 100ns");
-  Serial.printf("\nPlease connect GPIO %d to GPIO %d, now.\n", RMT_TX_PIN, RMT_RX_PIN);
-}
-
-void loop() {
-  // Init data
-  int i;
-  for (i = 0; i < 255; i++) {
-    data[i].val = 0x80010001 + ((i % 13) << 16) + 13 - (i % 13);
+  // create multiple pulses with different width to be sent
+  for (int i = 0; i < 255; i++) {
+    data[i].level0 = 1;                     // HIGH
+    data[i].duration0 = 1 + 13 - (i % 13);  // number of Tick on High
+    data[i].level1 = 0;                     // LOW
+    data[i].duration1 = 1 + (i % 13);       // number of Ticks on Low
     my_data[i].val = 0;
   }
   data[255].val = 0;
+  Serial.println();
+  Serial.println("====================================================================================================");
+  Serial.println("Preloaded Data that will sent (time in 0.1us):");
+  // Printout the received data plus the original values
+  for (int i = 0; i < RMT_NUM_EXCHANGED_DATA; i++) {
+    Serial.printf("%08lx=[%c 0x%02x|%c 0x%02x] ", data[i].val, data[i].level0 ? 'H' : 'L', data[i].duration0, data[i].level1 ? 'H' : 'L', data[i].duration1);
 
+    if (!((i + 1) % 4)) {
+      Serial.println();
+    }
+  }
+  Serial.println("====================================================================================================");
+  Serial.printf("Please connect GPIO %d to GPIO %d, now.", RMT_TX_PIN, RMT_RX_PIN);
+  Serial.println();
+  Serial.println();
+}
+
+void loop() {
   // Start an async data read
   size_t rx_num_symbols = RMT_NUM_EXCHANGED_DATA;
   rmtReadAsync(RMT_RX_PIN, my_data, &rx_num_symbols);
@@ -84,13 +97,13 @@ void loop() {
   Serial.printf("Got %d RMT symbols\n", rx_num_symbols);
 
   // Printout the received data plus the original values
-  for (i = 0; i < 60; i++) {
+  for (int i = 0; i < RMT_NUM_EXCHANGED_DATA; i++) {
     Serial.printf("%08lx=%08lx ", my_data[i].val, data[i].val);
     if (!((i + 1) % 4)) {
-      Serial.println("");
+      Serial.println();
     }
   }
-  Serial.println("\n");
+  Serial.println();
 
-  delay(500);
+  delay(2000);
 }