Merge pull request #4 from UT2UH/SDP810

SDP810 infrasound mic example added

Author: pschatzmann

sandbox/experiment-sdp810-serial/README.md

@@ -0,0 +1,15 @@
+# SDP810
+
+![SDP810](https://pschatzmann.github.io/arduino-audio-tools/doc/resources/ut2uh_sdp810_mic.jpeg)
+
+The SDP810 is a 16 bit differential pressure sensor connected via I2C.
+
+### Pins:
+ 
+| SDP810  | ESP32
+|---------|---------------
+| SCL     | SCL GPIO22
+| VDD     | 3.3
+| GND     | GND
+| SDA     | SDA GPIO21
+

sandbox/experiment-sdp810-serial/experiment-sdp810-serial.ino

@@ -0,0 +1,68 @@
+/**
+ *  Record output from SDP810 infrasonic microphone and send it to the Serial output 
+ * 
+ */
+
+#include <Wire.h>
+#include <SDPSensors.h> //https://github.com/UT2UH/SDP3x-Arduino/tree/SDP8x
+#include <AudioTools.h>
+
+using namespace audio_tools;
+typedef int16_t sound_t; // sound will be represented as int16_t
+
+const int sample_rate = 1024;
+const int buffer_size = 64;
+bool status;
+int16_t pressure;
+
+SDP8XX Mic = SDP8XX(Address5, DiffPressure, Wire);   
+TimerAlarmRepeating samplingTimer(1);
+NBuffer<int16_t> buffer(buffer_size, 3);
+
+// callback to record the sound data into a buffer
+void writeSample(void *ptr) {
+  status = Mic.readMeasurement(&pressure, NULL, NULL);
+  sound_t sample = pressure;
+  buffer.write(sample);
+}
+
+// Arduino Setup
+void setup(void) {
+  Serial.begin(115200);
+
+  // setup SDP810 infrasound microphone
+  Wire.begin();
+  Mic.begin();
+  Mic.startContinuous(false);
+
+  // start the timer to record the data
+  long waitUs = 1000000 / sample_rate;
+  samplingTimer.start(writeSample, waitUs, TimerAlarmRepeating::US);
+
+}
+
+void printSampleRate() {
+  static long next_time;
+  if (millis()>next_time){
+     next_time = next_time+1000;
+     Serial.print("sample rate: ");
+     Serial.println(buffer.sampleRate());
+  }
+}
+
+void printSamples() {
+  static sound_t array[buffer_size][2];
+  size_t len = buffer.readFrames(array);
+  for (int j=0;j<len;j++){
+    Serial.print(array[j][0]);
+    Serial.print(" ");
+    Serial.println(array[j][1]);
+  }
+}
+
+// Arduino loop - repeated processing
+void loop() {
+  // copy sound data from samples to Serial
+  printSamples();
+  printSampleRate();
+}

src/AudioTools.h

@@ -16,6 +16,6 @@
 #include "AudioTools/AudioI2S.h"
 #include "AudioTools/AnalogAudio.h"
 #include "AudioTools/AudioLogger.h"
-#include "AudioTools/Buffers.h"
+#include "AudioTools/TimerAlarmRepeating.h"
 #include "AudioTools/Streams.h"
 #include "AudioTools/AudioCopy.h"