Initial commit

.vscode/c_cpp_properties.json

@@ -0,0 +1,24 @@
+{
+    "configurations": [
+        {
+            "name": "Linux",
+            "includePath": [
+                "${workspaceFolder}/**",
+                "/home/dm1sh/.arduino15/packages/arduino/hardware/avr/1.8.5/cores/arduino",
+                "/home/dm1sh/.arduino15/packages/arduino/hardware/avr/1.8.5/variants/standard",
+                "/home/dm1sh/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/avr/include"
+            ],
+            "defines": [
+              "F_CPU=16000000",
+              "ARDUINO",
+              "ARDUINO_ARCH_AVR",
+              "__AVR_ATmega328P__"
+            ],
+            "compilerPath": "/home/dm1sh/.arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-gcc -mmcu= atmega328p",
+            "cStandard": "c11",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "clang-x64"
+        }
+    ],
+    "version": 4
+}

audio_player.ino

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+#include <avr/interrupt.h>
+#include <avr/io.h>
+#include <avr/pgmspace.h>
+
+#define SAMPLE_RATE 8000
+#define SPEAKER_PIN 11;
+
+#include "sounddata.h"
+
+volatile uint16_t smp_pos;
+uint8_t last_sample;
+
+void startPlayback() {
+  DDRB |= (1<<DDB3); // Setup 13th (led) pin for output
+  
+  // Setup timer2 to do PWM on pin 11 (OCR2A)
+  
+  // Use internal clock (disable async on timer2) (datasheet p.133)
+  ASSR &= ~((1<<EXCLK) | (1<<AS2));
+  
+  // Set fast PWM mode  (p.130)
+  TCCR2A |= (1<<WGM21) | (1<<WGM20);
+  TCCR2B &= ~(1<<WGM22);
+  
+  // Do non-inverting PWM on pin OC2A (p.128)
+  TCCR2A = (TCCR2A | (1<<COM2A1)) & ~(1<<COM2A0);
+  TCCR2A &= ~((1<<COM2B1) | (1<<COM2B0));
+  
+  // No prescaler (p.158)
+  TCCR2B = (TCCR2B & ~((1<<CS22) | (1<<CS21))) | (1<<CS20);
+  
+  // Set initial pulse width to the first sample.
+  OCR2A = pgm_read_byte(&sounddata_data[0]);
+  
+  
+  // Set up Timer 1 to send a sample every interrupt.
+  
+  cli();
+  
+  // Set CTC mode (Clear Timer on Compare Match) (p.110)
+  TCCR1B = (TCCR1B & ~(1<<WGM13)) | (1<<WGM12);
+  TCCR1A &= ~((1<<WGM11) | (1<<WGM10));
+  
+  // No prescaler (p.110)
+  TCCR1B = (TCCR1B & ~((1<<CS12) | (1<<CS11))) | (1<<CS10);
+  
+  // Set the 16-bit compare register (OCR1A).
+  OCR1A = F_CPU / SAMPLE_RATE;    // 16000000 / 8000 = 2000
+  
+  // Enable interrupt when TCNT1 == OCR1A (p.112)
+  TIMSK1 |= (1<<OCIE1A);
+
+  last_sample = pgm_read_byte(&sounddata_data[sounddata_length-1]);
+  
+  sei();
+}
+
+void stopPlayback()
+{
+  // Disable playback per-sample interrupt.
+  TIMSK1 &= ~(1<<OCIE1A);
+  
+  // Disable the per-sample timer completely.
+  TCCR1B &= ~(1<<CS10);
+  
+  // Disable the PWM timer.
+  TCCR2B &= ~(1<<CS20);
+  
+  PORTB |= (1<<PB3);
+
+  Serial.println("End");
+}
+
+void setup() {
+  startPlayback();
+  Serial.begin(9600);
+
+  Serial.println("Start");
+}
+
+// This is called at 8000 Hz to load the next sample.
+ISR(TIMER1_COMPA_vect) {
+  if (smp_pos < sounddata_length) {
+    OCR2A = pgm_read_byte(&sounddata_data[smp_pos]);
+  }
+  else {
+    if (smp_pos == sounddata_length + last_sample)
+      stopPlayback();
+    else
+      OCR2A = sounddata_length + last_sample - smp_pos;
+  }
+  
+  ++smp_pos;
+}
+
+void loop() {
+}