Redesign PWM output classes

Author: pschatzmann

examples/streams-generator-pwm/README.md

@@ -14,9 +14,9 @@ To test the output I am using a piezo electric element
 It should also be possible to connect a headphone to the output pins...
 
 
-On the ESP32 the output is on the Pins GPIO26 and GPIO27
+The pins depend on the Processor:
 
-| PIEZO     |  ESP32
-| --------| ---------------
-| +       |  GPIO22 / GPIO23
-| -       |  GND
+| PIEZO   |  ESP32         | AVR             | Rpi Pico
+| --------| ---------------|-----------------|--------------
+| +       |  GPIO3 / GPIO4 | GPIO3 / GPIO11  | GPIO03/GPIO04
+| -       |  GND           |                 |

examples/streams-generator-pwm/streams-generator-pwm.ino

@@ -15,7 +15,7 @@ int channels = 2;
 uint16_t sample_rate=22000;
 SineWaveGenerator<int16_t> sineWave(32000); // subclass of SoundGenerator with max amplitude of 32000
 GeneratedSoundStream<int16_t> sound(sineWave, channels);  // Stream generated from sine wave
-AudioPWM pwm;                  
+PWMAudioStream pwm;                  
 StreamCopy copier(pwm, sound);    // copy in to out
 
 
@@ -29,12 +29,12 @@ void setup() {
   // setup PWM output
   auto config = pwm.defaultConfig();
   config.sample_rate = sample_rate;
-  config.resolution = 8;  // must be between 8 and 11 -> drives pwm frequency (8 is default)
+  //config.resolution = 8;  // must be between 8 and 11 -> drives pwm frequency (8 is default)
   // alternative 1
   //config.channels = 2;  // not necesarry because 2 is default
-  //config.start_pin = 22;
+  //config.start_pin = 3;
   // alternative 2: defines pins and channels
-  config.setPins(pins); 
+  //config.setPins(pins); 
   pwm.begin(config);
 }
 

examples/streams-memory_wav-pwm/README.md

@@ -1,7 +1,13 @@
 # Decoding a WAV file
 
-In this example we decode a WAV file into RAW output and send it to a PWM pin on a Raspberry Pico
+In this example we decode a WAV file into RAW output and send it to a PWM pins (e.g. on a Raspberry Pico)
 
 MemoryStream -> AudioOutputStream -> WAVDecoder -> AudioPWM
 
-For the time beeing we just have an impelemntation of AudioPWM for the Rasperry Pico. But it should be possible to extend in to others as well in the future....
+The pins depend on the Processor:
+
+| PIEZO   |  ESP32         | AVR (Nano)      | Rpi Pico
+| --------| ---------------|-----------------|--------------
+| +       |  GPIO3 / GPIO4 | GPIO3 / GPIO11  | GPIO03/GPIO04
+| -       |  GND           |                 |
+

examples/streams-memory_wav-pwm/streams-memory_wav-pwm.ino

@@ -16,7 +16,7 @@ using namespace audio_tools;
 
 // MemoryStream -> AudioOutputStream -> WAVDecoder -> CsvStream
 MemoryStream wav(knghtsng_wav, knghtsng_wav_len);
-AudioPWM<int16_t> pwm;          // PWM output 
+PWMAudioStream pwm;          // PWM output 
 WAVDecoder decoder(pwm);        // decode wav to pcm and send it to printer
 AudioOutputStream out(decoder); // output to decoder
 StreamCopy copier(out, wav);    // copy in to out

src/AudioConfig.h

@@ -17,7 +17,7 @@
  */
 
 #define USE_AUDIO_LOGGING true
-#define PRINTF_BUFFER_SIZE 160
+#define PRINTF_BUFFER_SIZE 80
 #define LOG_LEVEL AudioLogger::Warning
 #define LOG_STREAM Serial
 
@@ -30,18 +30,18 @@
 #define LED_BUILTIN 13 // pin number is specific to your esp32 board
 #endif
 
-#define DEFAULT_BUFFER_SIZE 1024
+#define DEFAULT_BUFFER_SIZE 512
 #define DEFAULT_SAMPLE_RATE 44100
 #define DEFAULT_CHANNELS 2
 #define DEFAULT_BITS_PER_SAMPLE 16
 #define I2S_DEFAULT_PORT 0
-#define I2S_BUFFER_SIZE 1024
+#define I2S_BUFFER_SIZE 512
 #define I2S_BUFFER_COUNT 5
 #define A2DP_BUFFER_SIZE 4096
 #define A2DP_BUFFER_COUNT 8
 #define DEFAUT_ADC_PIN 34
-#define PWM_BUFFER_SIZE 1024
-#define PWM_BUFFERS 4
+#define PWM_BUFFER_SIZE 512
+#define PWM_BUFFERS 2
 
 /**
  * ------------------------------------------------------------------------- 

src/AudioPWM/PWMAudioStreamAVR.h

@@ -0,0 +1,141 @@
+
+#pragma once
+#include "AudioConfig.h"
+#ifdef __AVR__
+#include "AudioPWM/PWMAudioStreamBase.h"
+
+namespace audio_tools {
+
+class PWMAudioStreamAVR;
+typedef PWMAudioStreamAVR PWMAudioStream;
+static PWMAudioStreamAVR *accessAudioPWM = nullptr; 
+
+
+/**
+ * @brief Experimental: Audio output to PWM pins for the AVR. The AVR supports only up to 2 channels. 
+ * @author Phil Schatzmann
+ * @copyright GPLv3
+ */
+
+class PWMAudioStreamAVR : public PWMAudioStreamBase {
+    friend void defaultPWMAudioOutputCallback();
+
+    public:
+
+        PWMAudioStreamAVR(){
+            LOGD("PWMAudioStreamAVR");
+            accessAudioPWM = this;
+        }
+
+        virtual int maxChannels() {
+            return 2;
+        };
+
+        // Ends the output
+        virtual void end(){
+	 		LOGD(__FUNCTION__);
+            noInterrupts(); 
+            // stop timer callback
+            TCCR1B = 0;
+            // stop pwm timers
+            TCCR2A = 0;
+            interrupts(); // enable all interrupts
+
+            data_write_started = false;
+        }
+
+        /// Setup AVR timer with callback
+        void setupTimer() {
+	 		LOGD(__FUNCTION__);
+            // CPU Frequency 16 MHz
+            // prescaler 1, 256 or 1024 => no prescaling
+            uint32_t steps = F_CPU / 8 / audio_config.sample_rate;  // e.g. (16000000/8/44100=>45)
+            if (steps>65535){
+                LOGE("requested sample rate not supported: %d - we use %d",audio_config.sample_rate, F_CPU / 65536);
+                steps = 65535;
+            } else {
+                LOGD("compare match register set to %d",steps);
+            }
+
+            // setup timer intterupt
+            noInterrupts(); 
+            TCCR1B = 0;
+            //compare match register 
+            OCR1A = steps;
+            TCCR1B |= (1 << WGM12); // CTC mode
+            //TCCR1B |= (1 << CS10); // prescaler 1
+            TCCR1B |= (1 << CS11); // prescaler 8
+            TIMSK1 |= (1 << OCIE1A); // enable timer compare interrupt
+            interrupts(); // enable all interrupts
+        } 
+
+        /// Setup LED PWM
+        void setupPWM(){
+            LOGD(__FUNCTION__);
+            if (audio_config.channels>2) {
+                LOGW("Max 2 channels supported - you requested %d", audio_config.channels);
+                audio_config.channels = 2;
+            }
+
+            for (int j=0;j<audio_config.channels;j++){
+                LOGD("Processing channel %d", j);
+                setupPin(pins[j]);
+            }
+        }
+
+
+        // Timer 0 is used by Arduino!
+        // Timer 1 is used to drive output in sample_rate 
+        // => only Timer2 is available for PWM
+        void setupPin(int pin){
+            switch(pin){
+                case 3:case 11:
+                    // switch PWM frequency to 62500.00 Hz
+                    TCCR2B = TCCR2B & B11111000 | B00000001; 
+                    LOGI("PWM Frequency changed for D3 and D11");
+                    break;
+
+                default:
+                    LOGE("PWM Unsupported pin: %d", pin);
+                    break;
+
+            }
+            pinMode(pin, OUTPUT);
+        }
+
+        virtual void pwmWrite(int channel, int value){
+            analogWrite(pins[channel], value);
+        }
+
+        void logConfig(){
+            audio_config.logConfig();
+            LOGI("pwm freq: %f khz", 62.5);
+            if (audio_config.channels==1) {
+                LOGI("output pin: %d", pins[0]);
+            } else {
+                LOGI("output pins: %d / %d", pins[0],pins[1]);
+            }
+        }
+
+    protected:
+        int pins[2] =  {3, 11};
+      
+};
+
+/// separate method that can be defined as friend so that we can access protected information
+void defaultPWMAudioOutputCallback(){
+    if (accessAudioPWM!=nullptr && accessAudioPWM->data_write_started){
+        accessAudioPWM->playNextFrame();
+    }
+}
+
+/// timer callback: write the next frame to the pins
+ISR(TIMER1_COMPA_vect){
+    defaultPWMAudioOutputCallback();
+}
+
+} // Namespace
+
+
+#endif
+