Merge pull request #1 from trylaarsdam/recording

I2S recording functionality

README.md

@@ -32,17 +32,35 @@ i2s.begin();
 ```
 
 3. Play your audio buffer
+
+You can do this 2 ways - either by create a 16bit audio buffer and calling play:
 ```cpp
 i2s.play(buffer, bufferLen);
 ```
 
+Or you can also read a raw 8-bit PCM audio file, and provide it directly to i2s.play:
+```cpp
+#include "audio-file.h"
+i2s.play(audio_file_raw, audio_file_raw_len);
+```
+
+You can see documentation on how to generate such a file [here](https://dev.toddr.org/i2s-audio-playback-on-the-portenta-h7/).
+
+4. Record audio into a 32bit buffer
+```cpp
+#define BUFFER_LEN 8000 * 5 * 2 // 8000hz for 5 seconds for 2 channels (left, right)
+uint32_t rxBuffer[BUFFER_LEN];
+i2s.record(rxBuffer, BUFFER_LEN);
+```
+
 ## Examples
-A simple example is provided for both the M4 and M7 cores (usage is the same no matter the core), which plays a sine wave at 440.0Hz (A4) out of the I2S2 interface.
+
+Two examples are provided - one which generates and plays back a simple sine wave, and one which plays back a prerecorded audio file, records audio from the microphone immediately after, and then sends the recorded audio to the serial port, where you can parse it with Audacity as 32-bit signed PCM stereo audio. You can find a full guide [here](https://dev.toddr.org/i2s-audio-playback-on-the-portenta-h7/). 
 
 ## Playing audio files
 To play audio files, you can follow these steps:
 1. Open the audio file you want to play in Audacity (or equivalent software)
-2. Save the file as a RAW file with no headers, and in 16-bit signed PCM format
+2. Save the file as a RAW file with no headers, and in 8-bit signed PCM format
 3. On Linux/Mac, use `xxd` to create a C header file
 ```bash
 xxd -i {your-file.raw} > audio-file.h
@@ -51,23 +69,7 @@ xxd -i {your-file.raw} > audio-file.h
 5. Configure the I2S library with a sample rate that matches your audio file (important, otherwise your file will play at the wrong speed)
 6. Use this code to play the file
 ```cpp
-// calculate number of samples in the file
-unsigned int numSamples = audio_file_raw_len / 2;
-// Allocate memory for stereo samples (2 times larger than mono samples)
-uint16_t stereoSamples[8192];
-
-for(int i = 0; i < numSamples; i++){
-	int16_t rawSample = audio_file_raw[i * 2] | (audio_file_raw[i * 2 + 1] << 8);
-	// convert to unsigned 16 bit sample
-	stereoSamples[(i * 2) % 8192] = rawSample;
-	stereoSamples[((i * 2) % 8192) + 1] = rawSample;
-
-	if((i * 2) % 8192 == 0 && i != 0)
-	{
-		HAL_I2S_Transmit(&hi2s2, stereoSamples, 8192, HAL_MAX_DELAY);
- 	        delay(8192 / 22050 * 1000); // replace 22050 with your sample rate
-	}
-}
-```
+#include "audio-file.h"
 
-This will be an example soon.
+i2s.play(your_file_raw, your_file_raw_len);
+```

examples/playback-record/main.cpp

@@ -0,0 +1,36 @@
+#include "Arduino.h"
+#include <portenta-i2s.h>
+#include "ARTiE_Fork.h"
+
+#define I2S_BUFFER_SIZE I2S_AUDIOFREQ_8K * 5 * 2 // 5 seconds of audio, 2 channels
+
+PortentaI2S i2s = PortentaI2S(USE_I2S2, I2S_AUDIOFREQ_8K);
+
+uint32_t myBuffer[I2S_BUFFER_SIZE]; // RX buffer
+
+void setup()
+{
+	Serial.begin(115200); // Begin serial communication to send file
+	i2s.begin(); // Initialize I2S
+
+	i2s.play(ARTiE_Fork_raw, ARTiE_Fork_raw_len); // Play the 8bit signed audio file
+	i2s.record(myBuffer, I2S_BUFFER_SIZE); // Record 32bit signed audio into myBuffer for 5 seconds
+
+	// Print the recorded audio to serial
+	for(int i = 0; i < I2S_BUFFER_SIZE; i++)
+	{
+		if(i % 1 == 0) // 2 words per sample, 2 channels of data
+		{
+			volatile uint32_t sample = myBuffer[i];
+			sample = sample >> 14;
+			int32_t signedSample = sample; // center at 0
+			signedSample = sample * 65534; // scale to 32bit from 16bit
+			Serial.write((uint8_t*)&signedSample, sizeof(int32_t));
+		}
+	}
+}
+
+void loop()
+{
+	// do nothing
+}

examples/playback-record/platformio.ini

@@ -0,0 +1,24 @@
+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:portenta_h7_m7]
+build_type = debug
+platform = ststm32
+board = portenta_h7_m7
+framework = arduino
+upload_protocol = stlink
+debug_tool = stlink
+
+[env:portenta_h7_m4]
+platform = ststm32
+board = portenta_h7_m4
+framework = arduino
+upload_protocol = stlink
+debug_tool = stlink

examples/sine-wave/main.cpp

@@ -1,39 +1,3 @@
-#ifdef CORE_CM4
-
-#include <Arduino.h>
-#include <portenta-i2s.h>
-
-PortentaI2S i2s = PortentaI2S(USE_I2S2, I2S_AUDIOFREQ_44K);
-
-void setup()
-{
-	i2s.begin();
-
-	// Generate sine wave
-	uint16_t samplebuf[8192]; // for both left + right
-	const int nsamples = sizeof(samplebuf) / sizeof(samplebuf[0]);
-	int i = 0;
-	while(i < nsamples) {
-		double t = ((double)i / 2.0) / 44100.0;
-		samplebuf[i] = 32767*((sin((440.0 - FREQ_OFFSET) * TAU * t) / 2)); // left channel
-		samplebuf[i+1] = samplebuf[i]; // right channel (same)
-		i += 2;
-	}
-
-	// Play continuously
-	while(1){
-		i2s.play(samplebuf, nsamples);
-	}
-}
-
-void loop()
-{
-
-}
-
-#endif
-
-#ifdef CORE_CM7
 #include "Arduino.h"
 #include <portenta-i2s.h>
 
@@ -45,12 +9,12 @@ void setup()
 	i2s.begin();
 
 	// Generate sine wave
-	uint16_t samplebuf[8192]; // for both left + right
+	uint32_t samplebuf[8192]; // for both left + right
 	const int nsamples = sizeof(samplebuf) / sizeof(samplebuf[0]);
 	int i = 0;
 	while(i < nsamples) {
 		double t = ((double)i / 2.0) / 44100.0;
-		samplebuf[i] = 32767*((sin((440.0 - FREQ_OFFSET) * TAU * t) / 2)); // left channel
+		samplebuf[i] = 65536*((sin((440.0 - FREQ_OFFSET) * TAU * t) / 2)); // left channel
 		samplebuf[i+1] = samplebuf[i]; // right channel (same)
 		i += 2;
 	}
@@ -64,5 +28,4 @@ void setup()
 void loop()
 {
 
-}
-#endif
+}

library.json

@@ -1,6 +1,6 @@
 {
 	"name": "Portenta-I2S",
-	"version": "1.0.0",
+	"version": "1.1.0",
 	"description": "A simple I2S implementation using HAL for the Portenta H7 series.",
 	"repository":
   {