| // Adafruit Circuit Playground speaker library | |
| // by Phil Burgess / Paint Your Dragon. | |
| /**************************************************************************/ | |
| /*! | |
| @brief Sets up Circuit Playground speaker for PWM audio output: enables 48 KHz | |
| high-speed PWM mode, configures Timer/Counter 4, sets PWM duty cycle to | |
| 50% (speaker idle position). | |
| */ | |
| /**************************************************************************/ | |
| void Adafruit_CPlay_Speaker::begin(void) { | |
| if(!started) { | |
| // Set up Timer4 for fast PWM on !OC4A | |
| PLLFRQ = (PLLFRQ & 0xCF) | 0x30; // Route PLL to async clk | |
| TCCR4A = _BV(COM4A0) | _BV(PWM4A); // Clear on match, PWMA on | |
| TCCR4B = _BV(PWM4X) | _BV(CS40); // PWM invert, 1:1 prescale | |
| TCCR4D = 0; // Fast PWM mode | |
| TCCR4E = 0; // Not enhanced mode | |
| DT4 = 0; // No dead time | |
| noInterrupts(); // TC4H accesses must be atomic | |
| TC4H = 0; // Not 10-bit mode | |
| OCR4C = 255; // TOP | |
| TC4H = 0; | |
| OCR4A = 127; // 50% duty (idle position) to start | |
| interrupts(); | |
| pinMode(5, OUTPUT); // Enable output | |
| pinMode(CPLAY_SPEAKER_SHUTDOWN, OUTPUT); | |
| digitalWrite(CPLAY_SPEAKER_SHUTDOWN, HIGH); | |
| // PWM/timer not needed on CPlay Express, has true analog out. | |
| // Set analogWrite resolution to 8 bits to match AVR calls. | |
| analogWriteResolution(8); | |
| pinMode(A0, OUTPUT); // Enable output | |
| started = true; | |
| } | |
| } | |
| /**************************************************************************/ | |
| /*! | |
| @brief enable or disable the speaker. This function only works on 'Express' boards. | |
| @param e pass true to enable, false to disable | |
| */ | |
| /**************************************************************************/ | |
| void Adafruit_CPlay_Speaker::enable(bool e) { | |
| digitalWrite(CPLAY_SPEAKER_SHUTDOWN, e); | |
| } | |
| /**************************************************************************/ | |
| /*! | |
| @brief Turns off PWM output to the speaker. | |
| */ | |
| /**************************************************************************/ | |
| void Adafruit_CPlay_Speaker::end(void) { | |
| if(started) { | |
| TCCR4A = 0; // PWMA off | |
| pinMode(5, INPUT); | |
| pinMode(A0, INPUT); | |
| enable(false); | |
| started = false; | |
| } | |
| } | |
| /**************************************************************************/ | |
| /*! | |
| @brief Sets speaker position, enables PWM output if needed. | |
| @param value the value to set (0-255; 127=idle) | |
| */ | |
| /**************************************************************************/ | |
| void Adafruit_CPlay_Speaker::set(uint8_t value) { | |
| if(!started) begin(); | |
| OCR4A = value; | |
| analogWrite(A0, value); | |
| } | |
| /**************************************************************************/ | |
| /*! | |
| @brief Plays digitized 8-bit audio (optionally 10 bits on Express board) from | |
| a PROGMEM (flash memory) buffer. Maybe 1-3 seconds tops depending on | |
| sampling rate (e.g. 8000 Hz = 8 Kbytes/second). Max ~20K space avail on | |
| Circuit Playground, lots more on Circuit Playground Express. | |
| This function currently "blocks" -- it will not play sounds in the | |
| background while other code runs. | |
| @param data pointer to the audio data to play | |
| @param len the length of the data in samples | |
| @param sampleRate the sample rate of the data in samples per second | |
| @param tenBit Optional flag if true 10-bit mode is enabled. AVR ONLY | |
| */ | |
| /**************************************************************************/ | |
| void Adafruit_CPlay_Speaker::playSound( | |
| const uint8_t *data, uint32_t len, uint16_t sampleRate, bool tenBit) { | |
| uint32_t i; | |
| if(!started) begin(); | |
| uint16_t interval = 1000000L / sampleRate; | |
| uint32_t r2 = sampleRate / 2; | |
| uint32_t startTime = micros(); | |
| if(tenBit) { // 10-bit audio samples? | |
| uint8_t loIdx = 4; | |
| // Because it uses 8-bit PWM for output, the AVR code must filter | |
| // 10-bit data down to 8 bits. This is ONLY here for compatibility | |
| // with sketches with 10-bit samples. If targeting a project for AVR, | |
| // it's best to produce and use optimized 8-bit audio, else it's just | |
| // wasted space! Timer/Counter 4 DOES offer a 10-bit mode, but it's | |
| // not used in this library, just not worth it in the limited flash | |
| // space of the 32U4 chip. | |
| uint16_t idx = 0; | |
| uint8_t hiBits; | |
| for(i=0; i<len; i++) { | |
| if(++loIdx >= 4) { | |
| hiBits = pgm_read_byte(&data[idx++]); | |
| loIdx = 0; | |
| } | |
| OCR4A = ((hiBits & 0xC0) | (pgm_read_byte(&data[idx++]) >> 2)); | |
| hiBits <<= 2; // Do this after write, because of masking op above | |
| delayMicroseconds(interval); | |
| } | |
| OCR4A = 127; | |
| uint32_t idx = 0; | |
| uint16_t hiBits; | |
| analogWriteResolution(8); | |
| // Circuit Playground Express -- use 10-bit analogWrite() | |
| analogWriteResolution(10); | |
| for(i=0; i<len; i++) { | |
| if(++loIdx >= 4) { | |
| hiBits = (uint16_t)pgm_read_byte(&data[idx++]); | |
| loIdx = 0; | |
| } | |
| hiBits <<= 2; // Do this before write, because of masking op below | |
| analogWrite(A0, (hiBits & 0x300) | pgm_read_byte(&data[idx++])); | |
| while(((micros()-startTime+50)/100) < ((i*10000UL+r2)/sampleRate)); | |
| } | |
| analogWriteResolution(8); // Return to 8 bits for set() compatibility | |
| analogWrite(A0, 127); | |
| } else { // 8-bit audio samples | |
| for(i=0; i<len; i++) { | |
| OCR4A = pgm_read_byte(&data[i]); | |
| delayMicroseconds(interval); | |
| } | |
| OCR4A = 127; | |
| for(i=0; i<len; i++) { | |
| analogWrite(A0, pgm_read_byte(&data[i])); | |
| while(((micros()-startTime+50)/100) < ((i*10000UL+r2)/sampleRate)); | |
| } | |
| analogWrite(A0, 127); | |
| } | |
| } | |