Add I2S class support (#7874)

Fixes #427

Adds a basic I2S class based off of the Arduino-SAMD core.  The raw
i2s_xxx functions are still a better  way to use I2S due to their
flexibility, but this will allow basic Arduino sketches to work.

libraries/I2S/examples/InputSerialPlotter/InputSerialPlotter.ino

@@ -0,0 +1,36 @@
+/*
+  This example reads audio data from an Invensense's ICS43432 I2S microphone
+  breakout board, and prints out the samples to the Serial console. The
+  Serial Plotter built into the Arduino IDE can be used to plot the audio
+  data (Tools -> Serial Plotter)
+  created 17 November 2016
+  by Sandeep Mistry
+*/
+
+#include <I2S.h>
+
+void setup() {
+  // Open serial communications and wait for port to open:
+  // A baud rate of 115200 is used instead of 9600 for a faster data rate
+  // on non-native USB ports
+  Serial.begin(115200);
+  while (!Serial) {
+    ; // wait for serial port to connect. Needed for native USB port only
+  }
+
+  // start I2S at 8 kHz with 24-bits per sample
+  if (!I2S.begin(I2S_PHILIPS_MODE, 8000, 24)) {
+    Serial.println("Failed to initialize I2S!");
+    while (1); // do nothing
+  }
+}
+
+void loop() {
+  // read a sample
+  int sample = I2S.read();
+
+  if (sample) {
+    // if it's non-zero print value to serial
+    Serial.println(sample);
+  }
+}

libraries/I2S/examples/SimpleTone/SimpleTone.ino

@@ -0,0 +1,46 @@
+/*
+  This example generates a square wave based tone at a specified frequency
+  and sample rate. Then outputs the data using the I2S interface to a
+  MAX08357 I2S Amp Breakout board.
+
+  created 17 November 2016
+  by Sandeep Mistry
+  modified for ESP8266 by Earle F. Philhower, III <earlephilhower@yahoo.com>
+*/
+
+#include <I2S.h>
+
+const int frequency = 440; // frequency of square wave in Hz
+const int amplitude = 500; // amplitude of square wave
+const int sampleRate = 8000; // sample rate in Hz
+
+const int halfWavelength = (sampleRate / frequency); // half wavelength of square wave
+
+short sample = amplitude; // current sample value
+int count = 0;
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("I2S simple tone");
+
+  // start I2S at the sample rate with 16-bits per sample
+  if (!I2S.begin(I2S_PHILIPS_MODE, sampleRate, 16)) {
+    Serial.println("Failed to initialize I2S!");
+    while (1); // do nothing
+  }
+}
+
+void loop() {
+  if (count % halfWavelength == 0) {
+    // invert the sample every half wavelength count multiple to generate square wave
+    sample = -1 * sample;
+  }
+
+  // write the same sample twice, once for left and once for the right channel
+  I2S.write(sample);
+  I2S.write(sample);
+
+  // increment the counter for the next sample
+  count++;
+}
+

libraries/I2S/keywords.txt

@@ -0,0 +1,23 @@
+#######################################
+# Syntax Coloring Map I2S
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+
+I2S	KEYWORD1
+
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+begin	KEYWORD2
+end	KEYWORD2
+
+onReceive	KEYWORD2
+onTransmit	KEYWORD2
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+I2S_PHILIPS_MODE	LITERAL1

libraries/I2S/library.properties

@@ -0,0 +1,9 @@
+name=I2S
+version=1.0
+author=Earle F. Philhower, III <earlephilhower@yahoo.com>
+maintainer=Earle F. Philhower, III <earlephilhower@yahoo.com>
+sentence=Enables the communication with devices that use the Inter-IC Sound (I2S) Bus. Specific implementation for ESP8266, based off of SAMD.
+paragraph=
+category=Communication
+url=http://www.arduino.cc/en/Reference/I2S
+architectures=esp8266

libraries/I2S/src/I2S.cpp

@@ -0,0 +1,211 @@
+/*
+  Based off of ArduinoCore-SAMD I2S interface.  Modified for the
+  ESP8266 by Earle F. Philhower, III <earlephilhower@yahoo.com>
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include <Arduino.h>
+#include "I2S.h"
+
+I2SClass::I2SClass(bool enableTransmit, bool enableRecv, bool driveClocks) {
+  _enableTx = enableTransmit;
+  _enableRx = enableRecv;
+  _driveClk = driveClocks;
+  _running = false;
+  _onTransmit = nullptr;
+  _onReceive = nullptr;
+  _havePeeked = 0;
+  _peekedData = 0;
+  _bps = 0;
+  _writtenHalf = false;
+}
+
+int I2SClass::begin(i2s_mode_t mode, long sampleRate, int bitsPerSample) {
+  if ( _running || (mode != I2S_PHILIPS_MODE) || ( (bitsPerSample != 16) && (bitsPerSample != 24) ) ) {
+    return 0;
+  }
+  if (!i2s_rxtxdrive_begin(_enableRx, _enableTx, _driveClk, _driveClk)) {
+    return 0;
+  }
+  i2s_set_rate(sampleRate);
+  i2s_set_callback(_onTransmit);
+  i2s_rx_set_callback(_onReceive);
+  _bps = bitsPerSample;
+  _running = true;
+  return 1;
+}
+
+void I2SClass::end() {
+  if (_running) {
+    i2s_end();
+  }
+  i2s_set_callback(nullptr);
+  i2s_rx_set_callback(nullptr);
+  _running = false;
+}
+
+void I2SClass::onTransmit(void(*fcn)(void)) {
+  i2s_set_callback(fcn);
+  _onTransmit = fcn;
+}
+
+void I2SClass::onReceive(void(*fcn)(void)) {
+  i2s_rx_set_callback(fcn);
+  _onReceive = fcn;
+}
+
+int I2SClass::available() {
+  if (!_running) return 0;
+  return i2s_rx_available();
+}
+
+int I2SClass::availableForWrite() {
+  if (!_running) return 0;
+  return i2s_available();
+}
+
+void I2SClass::flush() {
+  /* No-op */
+}
+
+int I2SClass::read() {
+  if (!_running) return -1;
+  // Always just read from the peeked value to simplify operation
+  if (!_havePeeked) {
+    peek();
+  }
+  if (_havePeeked) {
+    if (_bps == 16) {
+      _havePeeked--;
+      int ret = _peekedData;
+      _peekedData >>= 16;
+      return ret;
+    } else /* _bps == 24 */ {
+      _havePeeked = 0;
+      return _peekedData;
+    }
+  }
+  return 0;
+}
+
+int I2SClass::peek() {
+  if (!_running) return -1;
+  if (_havePeeked) {
+    if (_bps == 16) {
+      int16_t sample = (int16_t)_peekedData; // Will extends sign on return
+      return sample;
+    } else {
+      return _peekedData;
+    }
+  }
+  int16_t l, r;
+  i2s_read_sample(&l, &r, true);
+  _peekedData = ((int)l << 16) | (0xffff & (int)r);
+  _havePeeked = 2; // We now have 2 16-bit quantities which can also be used as 1 32-bit(24-bit)
+  if (_bps == 16) {
+    return r;
+  } else {
+    return _peekedData;
+  }
+}
+
+int I2SClass::read(void *buffer, size_t size) {
+  if (!_running) return -1;
+  int cnt = 0;
+
+  if ( ((_bps == 24) && (size % 4)) || ((_bps == 16) && (size % 2)) || (size < 2) ) {
+    return 0; // Invalid, can only read in units of samples
+  }
+  // Make sure any peeked data is consumed first
+  if (_havePeeked) {
+    if (_bps == 16) {
+      while (_havePeeked && size) {
+        uint16_t *p = (uint16_t *)buffer;
+        *(p++) = _peekedData;
+        _peekedData >>= 16;
+        _havePeeked--;
+        buffer = (void *)p;
+        size -= 2;
+        cnt += 2;
+      }
+    } else {
+      uint32_t *p = (uint32_t *)buffer;
+      *(p++) = _peekedData;
+      buffer = (void *)p;
+      size -= 4;
+      cnt += 4;
+    }
+  }
+  // Now just non-blocking read up to the remaining size
+  int16_t l, r;
+  int16_t *p = (int16_t *)buffer;
+  while (size && i2s_read_sample(&l, &r, false)) {
+    *(p++) = l;
+    size--;
+    cnt++;
+    if (size) {
+      *(p++) = r;
+      size--;
+      cnt++;
+    } else {
+      // We read a simple we can't return, stuff it in the peeked data
+      _havePeeked = 1;
+      _peekedData = r;
+    }
+  }
+  return cnt;
+}
+
+size_t I2SClass::write(uint8_t s) {
+  if (!_running) return 0;
+  return write((int32_t)s);
+}
+
+size_t I2SClass::write(const uint8_t *buffer, size_t size) {
+  return write((const void *)buffer, size);
+}
+
+size_t I2SClass::write(int32_t s) {
+  if (!_running) return 0;
+  // Because our HW really wants 32b writes, store any 16b writes until another
+  // 16b write comes in and then send the combined write down.
+  if (_bps == 16) {
+    if (_writtenHalf) {
+      _writtenData <<= 16;
+      _writtenData |= 0xffff & s;
+      _writtenHalf = false;
+      return i2s_write_sample(_writtenData) ? 1 : 0;
+    } else {
+      _writtenHalf = true;
+      _writtenData = s & 0xffff;
+      return 1;
+    }
+  } else {
+    return i2s_write_sample((uint32_t)s) ? 1 : 0;
+  }
+}
+
+// SAMD core has this as non-blocking
+size_t I2SClass::write(const void *buffer, size_t size) {
+  if (!_running) return 0;
+  return i2s_write_buffer_nb((int16_t *)buffer, size / 2);
+}
+
+
+#if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_I2S)
+I2SClass I2S;
+#endif
+

libraries/I2S/src/I2S.h

@@ -0,0 +1,95 @@
+/*
+  Based off of ArduinoCore-SAMD I2S interface.  Modified for the
+  ESP8266 by Earle F. Philhower, III <earlephilhower@yahoo.com>
+
+  Copyright (c) 2016 Arduino LLC.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef _I2S_H_INCLUDED
+#define _I2S_H_INCLUDED
+
+#include <Arduino.h>
+#include <core_esp8266_i2s.h>
+
+typedef enum {
+  I2S_PHILIPS_MODE // Only mode allowed for now by the core
+} i2s_mode_t;
+
+class I2SClass : public Stream
+{
+public:
+  // By default only transmit and drive the clock pins
+  I2SClass(bool enableTransmit = true, bool enableRecv = false,
+           bool driveClocks = true);
+
+  // Only 16 and 24 bitsPerSample are allowed by the hardware
+  // 24-bit is MSB-aligned, with 0x00 in the lowest byte of each element.
+  int begin(i2s_mode_t mode, long sampleRate, int bitsPerSample);
+  void end();
+
+  // from Stream
+  virtual int available();
+  virtual int read(); // Blocking, will wait for incoming data
+  virtual int peek(); // Blocking, will wait for incoming data   
+  virtual void flush();
+
+  // from Print (see notes on write() methods below)
+  virtual size_t write(uint8_t);
+  virtual size_t write(const uint8_t *buffer, size_t size);
+  virtual int availableForWrite();
+
+  // Read up to size samples from the I2S device.  Non-blocking, will read
+  // from 0...size samples and return the count read.  Be sure your app handles
+  // the partial read case (i.e. yield()ing and trying to read more).
+  int read(void* buffer, size_t size);
+
+  // Write a single sample to the I2S device.  Blocking until write succeeds
+  size_t write(int32_t);
+  // Write up to size samples to the I2S device.  Non-blocking, will write
+  // from 0...size samples and return that count.  Be sure your app handles
+  // partial writes (i.e. by yield()ing and then retrying to write the
+  // remaining data.
+  size_t write(const void *buffer, size_t size);
+
+  // Note that these callback are called from **INTERRUPT CONTEXT** and hence
+  // must be both stored in IRAM and not perform anything that's not legal in
+  // an interrupt
+  void onTransmit(void(*)(void));
+  void onReceive(void(*)(void));
+
+private:
+  int _bps;
+  bool _running;
+  bool _enableTx;
+  bool _enableRx;
+  bool _driveClk;
+  void (*_onTransmit)(void);
+  void (*_onReceive)(void);
+  // Support for peek() on read path
+  uint32_t _peekedData;
+  int _havePeeked;
+  // Support for ::write(x) on 16b wuantities
+  uint32_t _writtenData;
+  bool _writtenHalf;
+};
+
+#if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_I2S)
+extern I2SClass I2S;
+#endif
+
+#endif
+