arduino-rx : first working example on RP2040 Connect !

examples/arduino-rx/arduino-rx.ino

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+#include "ggwave/ggwave.h"
+
+#include <PDM.h>
+
+// default number of output channels
+static const char channels = 1;
+
+// default PCM output frequency
+static const int frequency = 10000;
+
+const int qmax = 1024;
+volatile int qhead = 0;
+volatile int qtail = 0;
+volatile int qsize = 0;
+
+// Buffer to read samples into, each sample is 16-bits
+short sampleBuffer[qmax];
+
+// Number of audio samples read
+//volatile int samplesRead = 0;
+
+void setup() {
+    Serial.begin(57600);
+    while (!Serial);
+
+    // Configure the data receive callback
+    PDM.onReceive(onPDMdata);
+
+    // Optionally set the gain
+    // Defaults to 20 on the BLE Sense and -10 on the Portenta Vision Shields
+    //PDM.setGain(30);
+
+    // Initialize PDM with:
+    // - one channel (mono mode)
+    // - a 16 kHz sample rate for the Arduino Nano 33 BLE Sense
+    // - a 32 kHz or 64 kHz sample rate for the Arduino Portenta Vision Shields
+    if (!PDM.begin(channels, frequency)) {
+        Serial.println("Failed to start PDM!");
+        while (1);
+    }
+}
+
+volatile int err = 0;
+
+void loop() {
+    Serial.println("hello4");
+
+    //delay(1000);
+
+    Serial.println("trying to create ggwave instance");
+    //delay(1000);
+    auto p = GGWave::getDefaultParameters();
+    p.sampleRateInp = frequency;
+    p.sampleFormatInp = GGWAVE_SAMPLE_FORMAT_I16;
+    p.payloadLength = 4;
+    GGWave instance(p);
+
+    static GGWave::CBWaveformInp cbWaveformInp = [&](void * data, uint32_t nMaxBytes) {
+        if (2*qsize < nMaxBytes) {
+            return 0;
+        }
+        //Serial.println(nMaxBytes);
+        //Serial.println(qsize);
+        int nCopied = std::min((uint32_t) 2*qsize, nMaxBytes);
+        //Serial.println(qsize);
+        qsize -= nCopied / 2;
+        //Serial.println(nCopied);
+        //Serial.println("---------");
+        for (int i = 0; i < nCopied/2; ++i) {
+            //if (i == 0) Serial.println(sampleBuffer[qhead]);
+            //data[i] = sampleBuffer[qhead];
+            memcpy(((char *)data) + 2*i, (char *)(sampleBuffer + qhead), 2);
+            qhead = (qhead + 1) % qmax;
+        }
+        //std::copy((char *) sampleBuffer, ((char *) sampleBuffer) + nCopied, (char *) data);
+        return nCopied;
+    };
+
+    int nr = 0;
+    GGWave::TxRxData result;
+    while (true) {
+        //Serial.println(sampleBuffer[10]);
+        if (qsize >= 512) {
+            //Serial.println(sampleBuffer[10]);
+            //Serial.println(qsize);
+            instance.decode(cbWaveformInp);
+            nr = instance.takeRxData(result);
+            if (nr > 0) {
+                Serial.println(nr);
+                Serial.println((char *)result.data());
+            }
+            //samplesRead = 0;
+        }
+        if (err > 0) {
+            Serial.println("ERRROR");
+            Serial.println(err);
+        }
+    }
+}
+
+/**
+  Callback function to process the data from the PDM microphone.
+NOTE: This callback is executed as part of an ISR.
+Therefore using `Serial` to print messages inside this function isn't supported.
+ * */
+void onPDMdata() {
+    // Query the number of available bytes
+    int bytesAvailable = PDM.available();
+    int ns = bytesAvailable / 2;
+    if (qsize + ns > qmax) {
+        qhead = 0;
+        qtail = 0;
+        qsize = 0;
+    }
+
+    // Read into the sample buffer
+    PDM.read(sampleBuffer + qtail, bytesAvailable);
+
+    qtail += ns;
+    qsize += ns;
+    if (qtail > qmax) {
+        ++err;
+    }
+    if (qtail >= qmax) {
+        qtail -= qmax;
+    }
+}