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libraries/audio-tools/examples/sandbox/spi/spi-master/spi-master.ino

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+
+/**
+ * We use the default Arduino SPI API to send/write the data as SPI Master.
+ * For a sample rate of 44100 with 2 channels and 16 bit data you need to be
+ * able to transmit faster then 44100 * 2 channels * 2 bytes = 176400 bytes per
+ * second. Using a SPI communication this gives 176400 * 8 =
+ * 1'411'200 bps!
+ *
+ * Untested DRAFT implementation!
+ */
+#include <SPI.h>
+
+#include "AudioTools.h"
+
+const size_t BUFFER_SIZE = 1024;
+const int SPI_CLOCK = 2000000;  // 2 MHz
+AudioInfo info(44100, 2, 16);   //
+Vector<uint8_t> buffer(BUFFER_SIZE);
+SineWaveGenerator<int16_t> sineWave(32000);
+GeneratedSoundStream<int16_t> sound(sineWave);
+
+void setup() {
+  SPI.begin();
+  sineWave.begin(info, N_B4);
+  SPI.beginTransaction(SPISettings(SPI_CLOCK, MSBFIRST, SPI_MODE0));
+}
+
+void loop() {
+  // get data
+  size_t result = sound.readBytes(&buffer[0], buffer.size());
+  // transmit data
+  SPI.transfer(&buffer[0], result);
+  //SPI.endTransaction();
+}

libraries/audio-tools/examples/sandbox/spi/spi-slave-esp32/spi-slave-esp32.ino

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+/***
+ * We use the ESP32DMASPISlave library to implement the SPI slave on the ESP32
+ * which receives the data
+ * 
+ * Untested DRAFT implementation!
+ */
+#include <ESP32DMASPISlave.h>
+#include "AudioTools.h"
+
+const size_t BUFFER_SIZE = 1024;
+uint8_t *dma_rx_buf;
+ESP32DMASPI::Slave spi_slave;
+AudioInfo info(44100, 2, 16); //
+I2SStream out; // or replace with another output
+
+void setup() {
+  Serial.begin(115200);
+  // setup I2S
+  auto cfg = out.defaultConfig(TX_MODE);
+  cfg.copyFrom(info);
+  //cfg.pin_bck = 14;
+  //cfg.pin_ws = 15;
+  //cfg.pin_data = 22;
+  // to use DMA buffer, use these methods to allocate buffer
+  dma_rx_buf = spi_slave.allocDMABuffer(BUFFER_SIZE);
+
+  spi_slave.setDataMode(SPI_MODE0);           // default: SPI_MODE0
+  spi_slave.setMaxTransferSize(BUFFER_SIZE);  // default: 4092 bytes
+
+  // begin() after setting
+  spi_slave.begin();  // default: HSPI (please refer README for pin assignments)
+
+}
+
+void loop() {
+  // start and wait to complete one BIG transaction
+  size_t received_bytes = spi_slave.transfer(nullptr, dma_rx_buf, BUFFER_SIZE);
+  out.write(dma_rx_buf, received_bytes);
+}

libraries/audio-tools/examples/sandbox/spi/spi-slave-rp2040/spi-slave-rp2040

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+
+/***
+ * We use the RP2040 SPISlave to implement the SPI slave
+ * which receives the data
+ *
+ * Untested DRAFT implementation!
+ */
+#include <SPISlave.h>
+
+AudioInfo info(44100, 2, 16);  //
+I2SStream out;                 // or replace with another output
+
+// Wiring:
+// Master RX  GP0 <-> GP11  Slave TX
+// Master CS  GP1 <-> GP9   Slave CS
+// Master CK  GP2 <-> GP10  Slave CK
+// Master TX  GP3 <-> GP8   Slave RX
+
+SPISettings spisettings(2000000, MSBFIRST, SPI_MODE0);
+
+// Core 1 will be SPI slave
+void recvCallback(uint8_t *data, size_t len) { out.write(data, len); }
+
+void setup() {
+  Serial.begin(115200);
+
+  // setup I2S
+  auto cfg = out.defaultConfig(TX_MODE);
+  cfg.copyFrom(info);
+  // cfg.pin_bck = 14;
+  // cfg.pin_ws = 15;
+  // cfg.pin_data = 22;
+  out.begin(cfg);
+
+  // setup SPI
+  SPISlave.setRX(8);
+  SPISlave.setCS(9);
+  SPISlave.setSCK(10);
+  SPISlave.setTX(11);
+  // Hook our callbacks into the slave
+  SPISlave.onDataRecv(recvCallback);
+  SPISlave.begin(spisettings);
+
+  delay(1000);
+  Serial.println("SPISlave started");
+}
+
+void loop() {}