Cubetto Hardware
- ATSAMD21G18 microcontroller
- 32-Bit ARM Cortex M0+ at 48 MHz
- Flash Memory: 256 KB
- SRAM: 32 KB
- Compatible with the Arduino Zero board and can be programmed using the Arduino IDE as an Arduino Zero
- A buzzer is mounted on the Cubetto PCB and connected to Arduino pin number 17 (pin "A3" on the Arduino Zero and named "PA04" in the SAMD21 documentation)
Cubetto Firmware
Primo Video Guide to Updating the Cubetto Firmware Using the Arduino IDE:
Firmware Files
- Primo Cubetto Firmware: https://drive.google.com/file/d/0B0CGyWe9uilVc0Nycms2QnFJOTg/view (as referenced in the video above)
- GitHub repo of the firmware files: https://github.com/simonbates/cubetto
Speech Option 1: Text-To-Speech Library
- Talkie
- https://github.com/going-digital/Talkie
- PWM text-to-speech on 168 or 328 based Arduinos at 16MHz
- Modifications by Paul Stoffregen
- https://github.com/PaulStoffregen/Talkie
- https://forum.pjrc.com/threads/33446-Talkie-speech-library
- Supports DAC, PWM, and "propshield" outputs on Teensy LC, 3.1 & 3.2
- https://www.pjrc.com/teensy/teensyLC.html
- PWM on Teensy relies on the analogWriteFrequency() Teensy function
- TTS
- https://github.com/jscrane/TTS
- Does not support the SAMD21
Speech Option 2: Playback of Recorded Audio
Outline
- Prepare a recording of the word that we want to have Cubetto speak
- Store the audio data in our program by using 'xxd' to generate a C array notation for the audio data
- Use the Arduino PROGMEM keyword to store the audio data in flash storage, rather than RAM
Preparing Audio using eSpeak NG, FFmpeg, and xxd
We can use the eSpeak NG text-to-speech system to generate speech samples. For example to make a sample file for the word "forward":
> espeak-ng -v en -w forward.wav "forward"
The audio data from eSpeak NG is 16-bit at 22050 Hz in WAV file format:
> ffprobe forward.wav Input #0, wav, from 'forward.wav': Duration: 00:00:00.81, bitrate: 353 kb/s Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 22050 Hz, 1 channels, s16, 352 kb/s
Use FFmpeg to convert to 8-bit and strip the file header information:
> ffmpeg -i forward.wav -f u8 forward_u8_22050.raw
Make a C array notation version of the audio data with xxd:
> xxd -i forward_u8_22050.raw > forward_u8_22050.h
Change the array type to byte and add the PROGMEM keyword:
byte forward_u8_22050_raw[] PROGMEM = {
...
Option 2A: Playback using the SAMD21 DAC
Proof of Concept Code for MKR1000
// Based on
// https://github.com/arduino-libraries/AudioZero/blob/master/src/AudioZero.cpp
#include "forward_u8_22050.h"
byte* audioData;
uint32_t audioDataLen;
uint32_t sampleIndex;
void TC5_Handler (void) __attribute__ ((weak, alias("Play_Sample_Handler")));
bool tcIsSyncing()
{
return TC5->COUNT16.STATUS.reg & TC_STATUS_SYNCBUSY;
}
void resetTc()
{
TC5->COUNT16.CTRLA.reg = TC_CTRLA_SWRST;
while (tcIsSyncing());
while (TC5->COUNT16.CTRLA.bit.SWRST);
}
void disableTc()
{
TC5->COUNT16.CTRLA.reg &= ~TC_CTRLA_ENABLE;
while (tcIsSyncing());
}
void configureTc(uint32_t sampleRate)
{
// Enable GCLK for TCC2 and TC5 (timer counter input clock)
GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID(GCM_TC4_TC5)) ;
while (GCLK->STATUS.bit.SYNCBUSY);
resetTc();
// Set Timer counter Mode to 16 bits
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16;
// Set TC5 mode as match frequency
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_WAVEGEN_MFRQ;
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_PRESCALER_DIV1 | TC_CTRLA_ENABLE;
TC5->COUNT16.CC[0].reg = (uint16_t) (SystemCoreClock / sampleRate - 1);
while (tcIsSyncing());
// Configure interrupt request
NVIC_DisableIRQ(TC5_IRQn);
NVIC_ClearPendingIRQ(TC5_IRQn);
NVIC_SetPriority(TC5_IRQn, 0);
NVIC_EnableIRQ(TC5_IRQn);
// Enable the TC5 interrupt request
TC5->COUNT16.INTENSET.bit.MC0 = 1;
while (tcIsSyncing());
}
void playSample(byte* data, uint32_t length, uint32_t sampleRate)
{
pinMode(PIN_A0, OUTPUT);
analogWriteResolution(8);
audioData = data;
audioDataLen = length;
sampleIndex = 0;
configureTc(sampleRate);
}
void stopPlaying()
{
resetTc();
disableTc();
}
void sayForward()
{
playSample(forward_u8_22050_raw, forward_u8_22050_raw_len, 22050);
delay(3000);
stopPlaying();
}
void setup() {
}
void loop() {
sayForward();
delay(4000);
}
#ifdef __cplusplus
extern "C" {
#endif
void Play_Sample_Handler (void)
{
if (sampleIndex < audioDataLen - 1) {
analogWrite(PIN_A0, pgm_read_byte_far(audioData + sampleIndex));
++sampleIndex;
// Clear the interrupt
TC5->COUNT16.INTFLAG.bit.MC0 = 1;
} else {
// This will loop until stopPlaying() is called
sampleIndex = 0;
TC5->COUNT16.INTFLAG.bit.MC0 = 1;
}
}
#ifdef __cplusplus
}
#endif
GitHub: https://github.com/simonbates/arduino-audio-examples/blob/master/samd21_dac_sampled_audio
Option 2B: Playback using PWM
Proof of Concept Code for MKR1000
// PWM based on code from MartinL in
// https://forum.arduino.cc/index.php?topic=346731.0
// Sample playback based on
// https://github.com/arduino-libraries/AudioZero/blob/master/src/AudioZero.cpp
#include "forward_u8_22050.h"
byte* audioData;
uint32_t audioDataLen;
uint32_t sampleIndex;
void TC5_Handler (void) __attribute__ ((weak, alias("Play_Sample_Handler")));
bool tcIsSyncing()
{
return TC5->COUNT16.STATUS.reg & TC_STATUS_SYNCBUSY;
}
void resetTc()
{
TC5->COUNT16.CTRLA.reg = TC_CTRLA_SWRST;
while (tcIsSyncing());
while (TC5->COUNT16.CTRLA.bit.SWRST);
}
void disableTc()
{
TC5->COUNT16.CTRLA.reg &= ~TC_CTRLA_ENABLE;
while (tcIsSyncing());
}
void configureTc(uint32_t sampleRate)
{
// Enable GCLK for TCC2 and TC5 (timer counter input clock)
GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID(GCM_TC4_TC5)) ;
while (GCLK->STATUS.bit.SYNCBUSY);
resetTc();
// Set Timer counter Mode to 16 bits
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16;
// Set TC5 mode as match frequency
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_WAVEGEN_MFRQ;
TC5->COUNT16.CTRLA.reg |= TC_CTRLA_PRESCALER_DIV1 | TC_CTRLA_ENABLE;
TC5->COUNT16.CC[0].reg = (uint16_t) (SystemCoreClock / sampleRate - 1);
while (tcIsSyncing());
// Configure interrupt request
NVIC_DisableIRQ(TC5_IRQn);
NVIC_ClearPendingIRQ(TC5_IRQn);
NVIC_SetPriority(TC5_IRQn, 0);
NVIC_EnableIRQ(TC5_IRQn);
// Enable the TC5 interrupt request
TC5->COUNT16.INTENSET.bit.MC0 = 1;
while (tcIsSyncing());
}
void playSample(byte* data, uint32_t length, uint32_t sampleRate)
{
audioData = data;
audioDataLen = length;
sampleIndex = 0;
configureTc(sampleRate);
}
void stopPlaying()
{
resetTc();
disableTc();
}
void sayForward()
{
playSample(forward_u8_22050_raw, forward_u8_22050_raw_len, 22050);
delay(3000);
stopPlaying();
}
void setup()
{
REG_GCLK_GENDIV = GCLK_GENDIV_DIV(1) | // Divide the 48MHz clock source by divisor 1: 48MHz/1=48MHz
GCLK_GENDIV_ID(4); // Select Generic Clock (GCLK) 4
while (GCLK->STATUS.bit.SYNCBUSY); // Wait for synchronization
REG_GCLK_GENCTRL = GCLK_GENCTRL_IDC | // Set the duty cycle to 50/50 HIGH/LOW
GCLK_GENCTRL_GENEN | // Enable GCLK4
GCLK_GENCTRL_SRC_DFLL48M | // Set the 48MHz clock source
GCLK_GENCTRL_ID(4); // Select GCLK4
while (GCLK->STATUS.bit.SYNCBUSY); // Wait for synchronization
// Enable the port multiplexer for the digital pin D7
PORT->Group[g_APinDescription[7].ulPort].PINCFG[g_APinDescription[7].ulPin].bit.PMUXEN = 1;
// Connect the TCC0 timer to digital output D7 - port pins are paired odd PMUO and even PMUXE
// F & E specify the timers: TCC0, TCC1 and TCC2
PORT->Group[g_APinDescription[6].ulPort].PMUX[g_APinDescription[6].ulPin >> 1].reg = PORT_PMUX_PMUXO_F;
// Feed GCLK4 to TCC0 and TCC1
REG_GCLK_CLKCTRL = GCLK_CLKCTRL_CLKEN | // Enable GCLK4 to TCC0 and TCC1
GCLK_CLKCTRL_GEN_GCLK4 | // Select GCLK4
GCLK_CLKCTRL_ID_TCC0_TCC1; // Feed GCLK4 to TCC0 and TCC1
while (GCLK->STATUS.bit.SYNCBUSY); // Wait for synchronization
// Dual slope PWM operation: timers countinuously count up to PER register value then down 0
REG_TCC0_WAVE |= TCC_WAVE_POL(0xF) | // Reverse the output polarity on all TCC0 outputs
TCC_WAVE_WAVEGEN_DSBOTH; // Setup dual slope PWM on TCC0
while (TCC0->SYNCBUSY.bit.WAVE); // Wait for synchronization
// Each timer counts up to a maximum or TOP value set by the PER register,
// this determines the frequency of the PWM operation:
REG_TCC0_PER = 255;
while (TCC0->SYNCBUSY.bit.PER); // Wait for synchronization
REG_TCC0_CC3 = 0; // TCC0 CC3 - on D7
while (TCC0->SYNCBUSY.bit.CC3); // Wait for synchronization
// Divide the 48MHz signal by 1 giving 48MHz TCC0 timer tick and enable the outputs
REG_TCC0_CTRLA |= TCC_CTRLA_PRESCALER_DIV1 | // Divide GCLK4 by 1
TCC_CTRLA_ENABLE; // Enable the TCC0 output
while (TCC0->SYNCBUSY.bit.ENABLE); // Wait for synchronization
}
void loop() {
sayForward();
delay(4000);
}
#ifdef __cplusplus
extern "C" {
#endif
void Play_Sample_Handler (void)
{
if (sampleIndex < audioDataLen - 1) {
// TCC0 CC3 - on D7
REG_TCC0_CC3 = pgm_read_byte_far(audioData + sampleIndex);
++sampleIndex;
// Clear the interrupt
TC5->COUNT16.INTFLAG.bit.MC0 = 1;
} else {
// This will loop until stopPlaying() is called
sampleIndex = 0;
TC5->COUNT16.INTFLAG.bit.MC0 = 1;
}
}
#ifdef __cplusplus
}
#endif
GitHub: https://github.com/simonbates/arduino-audio-examples/tree/master/samd21_pwm_sampled_audio
Resources
SAMD21 Product Information and Datasheet
Arduino Memory
- https://www.arduino.cc/reference/en/language/variables/utilities/progmem/
- http://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html