2 more examples for NRF52

- Add radio transmission & reception examples using both PWM and I2S output

examples/Platforms/NRF52/NRF52_Radio/NRF52_PWM_I2S_RadioRX/NRF52_PWM_I2S_RadioRX.ino

@@ -0,0 +1,46 @@
+/* Example of receiving audio over radio and playing it back. 
+ * Note: This example uses I2S output. Modify the USE_I2S #define
+ * below to enable PWM output.
+ */ 
+
+#include <AutoAnalogAudio.h>
+#include <nrf_to_nrf.h>
+
+AutoAnalog aaAudio;
+nrf_to_nrf radio;
+
+uint8_t address[][6] = { "1Node", "2Node" };
+#define BUFFER_SIZE 125
+#define USE_I2S 0 // Change to 1 to enable I2S output instead of PWM
+
+void setup() {
+
+  Serial.begin(115200);
+
+  radio.begin();
+  radio.setPayloadSize(BUFFER_SIZE);
+  radio.setAutoAck(0);
+  radio.setDataRate(NRF_2MBPS);
+  radio.openReadingPipe(1,address[1]);
+  radio.startListening();
+
+  Serial.println("Analog Audio Begin");
+  aaAudio.begin(0, 1, USE_I2S);  //Setup aaAudio using DAC and PWM. Change the third value to a 1 to enable I2S
+
+  //Setup for audio: Use 8-bit, mono WAV files @ 16kHz
+  aaAudio.dacBitsPerSample = 8;    // 8-bit
+  aaAudio.setSampleRate(16000, 0); // 16khz, mono
+
+  pinMode(6,OUTPUT); // For I2S output: Connected to SD pin of MAX98357A
+  digitalWrite(6,HIGH);
+
+}
+
+void loop() {
+
+  if(radio.available()){
+    radio.read(&aaAudio.dacBuffer[0],BUFFER_SIZE);
+    aaAudio.feedDAC(0,BUFFER_SIZE);
+  }
+
+}

examples/Platforms/NRF52/NRF52_Radio/NRF52_SD_I2S_RadioTX/NRF52_SD_I2S_RadioTX.ino

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+/* Example of reading audio from SD card and sending over radio
+ * Note: This example uses I2S output. Modify the USE_I2S #define
+ * below to enable PWM output.
+ */ 
+
+#include <SPI.h>
+#include <SD.h>
+#include <AutoAnalogAudio.h>
+#include <nrf_to_nrf.h>
+
+AutoAnalog aaAudio;
+nrf_to_nrf radio;
+
+uint8_t address[][6] = { "1Node", "2Node" };
+#define BUFFER_SIZE 125
+#define USE_I2S 1 // Change to 0 to enable PWM output instead of I2S
+
+/*********************************************************/
+/* Tested with MAX98357A I2S breakout on XIAO 52840 Sense
+/* BCLK connected to Arduino D1 (p0.03)
+/* LRCK connected to Arduino D3 (p0.29)
+/* DIN  connected to Arduino D5 (p0.05)
+/* SD   connected to Arduino D6 (p1.11)
+/*********************************************************/
+
+void setup() {
+
+  Serial.begin(115200);
+
+  radio.begin();
+  radio.setPayloadSize(BUFFER_SIZE);
+  radio.setAutoAck(0);
+  radio.setDataRate(NRF_2MBPS);
+  radio.openWritingPipe(address[1]);
+  radio.stopListening();
+
+  Serial.print("Init SD card...");
+  if (!SD.begin(10000000, 2)) {
+    Serial.println("init failed!");
+    return;
+  }
+  Serial.println("init ok");
+  Serial.println("Analog Audio Begin");
+  aaAudio.begin(0, 1, USE_I2S);  //Setup aaAudio using DAC and I2S
+
+  //Setup for audio: Use 8-bit, mono WAV files @ 16kHz
+  aaAudio.dacBitsPerSample = 8;     // 8-bit
+  aaAudio.setSampleRate(16000, 0);  // 16khz, mono
+
+  pinMode(6, OUTPUT);  //Connected to SD pin of MAX98357A
+  digitalWrite(6, HIGH);
+
+  playAudio("guitar/g8b16km.wav");  // 16kHz @ 8-bits is about the maximum when reading from SD card & streaming over radio
+}
+
+void loop() {
+
+  loadBuffer();
+}
+
+/*********************************************************/
+/* A simple function to handle playing audio files
+/*********************************************************/
+
+File myFile;
+
+void playAudio(const char *audioFile) {
+
+  if (myFile) {
+    myFile.close();
+  }
+  //Open the designated file
+  myFile = SD.open(audioFile);
+  //Skip past the WAV header
+  myFile.seek(44);
+}
+
+void loadBuffer() {
+
+  if (myFile.available()) {
+    myFile.read(aaAudio.dacBuffer, BUFFER_SIZE);  // Change this to dacBuffer16 for 16-bit samples
+    aaAudio.feedDAC(0, BUFFER_SIZE);
+    radio.startWrite(&aaAudio.dacBuffer[0], BUFFER_SIZE, 1);
+  } else {
+    myFile.seek(44);
+  }
+}