Add PWMAudio support for the RP2040 (#597)

Uses the RP2040 HW PWM generator to provide a stereo audio signal.

examples/PlayMODFromPROGMEMToPWM/PlayMODFromPROGMEMToPWM.ino

@@ -0,0 +1,47 @@
+#include <Arduino.h>
+#include "AudioFileSourcePROGMEM.h"
+#include "AudioGeneratorMOD.h"
+#include "AudioOutputPWM.h"
+
+#if !defined(ARDUINO_ARCH_RP2040)
+void setup() {
+  Serial.begin(115200);
+  Serial.printf("Only for the RP2040/Raspberry Pi Pico\n");
+}
+
+void loop() {
+}
+#else
+
+// 5_steps.mod sample from the mod archive: https://modarchive.org/
+#include "5steps.h"
+
+AudioGeneratorMOD *mod;
+AudioFileSourcePROGMEM *file;
+AudioOutputPWM *out;
+
+void setup()
+{
+  Serial.begin(115200);
+  delay(1000);
+
+  audioLogger = &Serial;
+  file = new AudioFileSourcePROGMEM(steps_mod, sizeof(steps_mod));
+  out = new AudioOutputPWM();
+  mod = new AudioGeneratorMOD();
+  mod->SetBufferSize(3*1024);
+  mod->SetSampleRate(44100);
+  mod->SetStereoSeparation(32);
+  mod->begin(file, out);
+}
+
+void loop()
+{
+  if (mod->isRunning()) {
+    if (!mod->loop()) mod->stop();
+  } else {
+    Serial.printf("MOD done\n");
+    delay(1000);
+  }
+}
+#endif

keywords.txt

@@ -23,6 +23,7 @@ AudioOutput	KEYWORD1
 AudioOutputI2S	KEYWORD1
 AudioOutputI2SNoDAC	KEYWORD1
 AudioOutputI2SClass	KEYWORD1
+AudioOutputPWM	KEYWORD1
 AudioOutputNull	KEYWORD1
 AudioOutputBuffer	KEYWORD1
 AudioOutputSerialWAV	KEYWORD1

src/AudioGeneratorWAV.cpp

@@ -127,7 +127,7 @@ bool AudioGeneratorWAV::ReadWAVInfo()
     return false;
   };
   if (u32 != 0x46464952) {
-    Serial.printf_P(PSTR("AudioGeneratorWAV::ReadWAVInfo: cannot read WAV, invalid RIFF header, got: %08X \n"), (uint32_t) u32);
+    Serial.printf_P(PSTR("AudioGeneratorWAV::ReadWAVInfo: cannot read WAV, invalid RIFF header\n"));
     return false;
   }
 
@@ -143,7 +143,7 @@ bool AudioGeneratorWAV::ReadWAVInfo()
     return false;
   };
   if (u32 != 0x45564157) {
-    Serial.printf_P(PSTR("AudioGeneratorWAV::ReadWAVInfo: cannot read WAV, invalid WAVE header, got: %08X \n"), (uint32_t) u32);
+    Serial.printf_P(PSTR("AudioGeneratorWAV::ReadWAVInfo: cannot read WAV, invalid WAVE header\n"));
     return false;
   }
 

src/AudioOutputPWM.cpp

@@ -0,0 +1,114 @@
+/*
+  AudioOutputPWM
+  Base class for the RP2040 PWM audio
+  
+  Copyright (C) 2023  Earle F. Philhower, III
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#if defined(ARDUINO_ARCH_RP2040)
+#include <Arduino.h>
+#include "AudioOutputPWM.h"
+
+AudioOutputPWM::AudioOutputPWM(long sampleRate, pin_size_t data) {
+    pwmOn = false;
+    mono = false;
+    bps = 16;
+    channels = 2;
+    hertz = sampleRate;
+    doutPin = data;
+    SetGain(1.0);
+    pwm.setStereo(true);
+}
+
+AudioOutputPWM::~AudioOutputPWM() {
+  stop();
+}
+
+bool AudioOutputPWM::SetRate(int hz) {
+  this->hertz = hz;
+  if (pwmOn) {
+      pwm.setFrequency(hz);
+  }
+  return true;
+}
+
+bool AudioOutputPWM::SetBitsPerSample(int bits) {
+  if ( (bits != 16) && (bits != 8) ) return false;
+  this->bps = bits;
+  return true;
+}
+
+bool AudioOutputPWM::SetChannels(int channels) {
+  if ( (channels < 1) || (channels > 2) ) return false;
+  this->channels = channels;
+  return true;
+}
+
+bool AudioOutputPWM::SetOutputModeMono(bool mono) {
+  this->mono = mono;
+  return true;
+}
+
+bool AudioOutputPWM::begin() {
+  if (!pwmOn) {
+    pwm.setPin(doutPin);
+    pwm.begin(hertz);
+  }
+  pwmOn = true;
+  SetRate(hertz); // Default
+  return true;
+}
+
+bool AudioOutputPWM::ConsumeSample(int16_t sample[2]) {
+
+  if (!pwmOn)
+    return false;
+
+  int16_t ms[2];
+
+  ms[0] = sample[0];
+  ms[1] = sample[1];
+  MakeSampleStereo16( ms );
+
+  if (this->mono) {
+    // Average the two samples and overwrite
+    int32_t ttl = ms[LEFTCHANNEL] + ms[RIGHTCHANNEL];
+    ms[LEFTCHANNEL] = ms[RIGHTCHANNEL] = (ttl>>1) & 0xffff;
+  }
+
+  if (pwm.available()) {
+      pwm.write((int16_t) ms[0]);
+      pwm.write((int16_t) ms[1]);
+      return true;
+  } else {
+      return false;
+  }
+}
+
+void AudioOutputPWM::flush() {
+  pwm.flush();
+}
+
+bool AudioOutputPWM::stop() {
+  if (!pwmOn)
+    return false;
+
+  pwm.end();
+  pwmOn = false;
+  return true;
+}
+
+#endif

src/AudioOutputPWM.h

@@ -0,0 +1,57 @@
+/*
+  AudioOutputPWM
+  Base class for the RP2040 PWM audio output
+  
+  Copyright (C) 2023  Earle F. Philhower, III
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include "AudioOutput.h"
+
+#if defined(ARDUINO_ARCH_RP2040)
+#include <Arduino.h>
+#include <PWMAudio.h>
+
+class AudioOutputPWM : public AudioOutput
+{
+  public:
+    AudioOutputPWM(long sampleRate = 44100, pin_size_t data = 0);
+    virtual ~AudioOutputPWM() override;
+    virtual bool SetRate(int hz) override;
+    virtual bool SetBitsPerSample(int bits) override;
+    virtual bool SetChannels(int channels) override;
+    virtual bool begin() override;
+    virtual bool ConsumeSample(int16_t sample[2]) override;
+    virtual void flush() override;
+    virtual bool stop() override;
+
+    bool SetOutputModeMono(bool mono);  // Force mono output no matter the input
+
+  protected:
+    bool SetPinout();
+    virtual int AdjustI2SRate(int hz) { return hz; }
+    uint8_t portNo;
+    int output_mode;
+    bool mono;
+    bool pwmOn;
+
+    uint8_t doutPin;
+
+    PWMAudio pwm;
+};
+
+#endif

src/ESP8266Audio.h

@@ -41,6 +41,7 @@
 #include "AudioOutput.h"
 #include "AudioOutputI2S.h"
 #include "AudioOutputI2SNoDAC.h"
+#include "AudioOutputPWM.h"
 #include "AudioOutputMixer.h"
 #include "AudioOutputNull.h"
 #include "AudioOutputSerialWAV.h"

tests/common.sh

@@ -109,7 +109,11 @@ if [ "$BUILD_TYPE" = "build" ]; then
     install_arduino
     install_esp8266 "$HOME/arduino_ide"
     source "$HOME/arduino_ide/hardware/esp8266com/esp8266/tests/common.sh"
-    build_sketches "$HOME/arduino_ide" "$TRAVIS_BUILD_DIR" "-l $HOME/Arduino/libraries" "$BUILD_MOD" "$BUILD_REM" "lm2f"
+    export ESP8266_ARDUINO_SKETCHES=$(find $HOME/Arduino/libraries/ESP8266Audio -name *.ino | sort)
+    # ESP8266 scripts now expect tools in wrong spot.  Use simple and dumb fix
+    mkdir -p "$HOME/work/ESP8266Audio/ESP8266Audio"
+    ln -s "$HOME/arduino_ide/hardware/esp8266com/esp8266/tools" "$HOME/work/ESP8266Audio/ESP8266Audio/tools"
+    build_sketches "$TRAVIS_BUILD_DIR" "$HOME/arduino_ide" "$HOME/arduino_ide/hardware" "$HOME/Arduino/libraries" "$BUILD_MOD" "$BUILD_REM" "lm2f"
 elif [ "$BUILD_TYPE" = "build_esp32" ]; then
     install_arduino
     install_esp32 "$HOME/arduino_ide"