140 lines
4.4 KiB
C++
140 lines
4.4 KiB
C++
// References / Resources / Inspiration
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// https://gist.github.com/nonsintetic/ad13e70f164801325f5f552f84306d6f
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// Varous system includes
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#include <Arduino.h>
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#include "wiring_private.h"
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// Various library includes
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#include <CircularBuffer.h>
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// Buffer for serial data -> i2c
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#define UART_BUFFER_SIZE 16 * 1024
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CircularBuffer<char,UART_BUFFER_SIZE> uartBuffer;
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// Board LED Pin
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#define PIN_BOARD_LED 13
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// Blinking timer setup
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#define TIMER_MILLIS 500
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bool ledState = false;
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void TC5_Handler(void);
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void timerConfigure(int sampleRate);
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// Additional serial ports for communication <> RPI
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// https://learn.adafruit.com/using-atsamd21-sercom-to-add-more-spi-i2c-serial-ports?view=all#creating-a-new-serial
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// RX -- A2 -- S 4:1
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// TX -- A1 -- S 4:0
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// RX -- 10 -- S 3:2
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// TX -- 11 -- S 3:0
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Uart rpiUART0 (&sercom4, A1, A2, SERCOM_RX_PAD_1, UART_TX_PAD_0);
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Uart rpiUART5 (&sercom3, 10, 11, SERCOM_RX_PAD_2, UART_TX_PAD_0);
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void SERCOM4_Handler() {
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rpiUART0.IrqHandler();
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}
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void SERCOM3_Handler() {
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rpiUART5.IrqHandler();
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}
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// Setup stuff needed for build
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void setup() {
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// Setup board LED
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pinMode(PIN_BOARD_LED, OUTPUT);
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// Timer setup
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timerConfigure(TIMER_MILLIS);
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timerStartCounter();
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// Assign SERCOM functionality
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pinPeripheral(A1, PIO_SERCOM);
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pinPeripheral(A2, PIO_SERCOM);
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pinPeripheral(10, PIO_SERCOM);
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pinPeripheral(11, PIO_SERCOM);
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// Setup serial ports
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Serial.begin(115200);
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rpiUART0.begin(115200);
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rpiUART5.begin(115200);
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}
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// Main function
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void loop() {
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digitalWrite(PIN_BOARD_LED, HIGH);
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delay(500);
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digitalWrite(PIN_BOARD_LED, LOW);
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delay(500);
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}
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// Timer handler
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void TC5_Handler (void) {
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if(ledState == true) {
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digitalWrite(PIN_BOARD_LED, HIGH);
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} else {
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digitalWrite(PIN_BOARD_LED, LOW);
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}
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ledState = !ledState;
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TC5->COUNT16.INTFLAG.bit.MC0 = 1; //Writing a 1 to INTFLAG.bit.MC0 clears the interrupt so that it will run again
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}
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//Configures the TC to generate output events at the sample frequency.
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//Configures the TC in Frequency Generation mode, with an event output once
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//each time the audio sample frequency period expires.
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void timerConfigure(int sampleRate) {
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// select the generic clock generator used as source to the generic clock multiplexer
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GCLK->CLKCTRL.reg = (uint16_t) (GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK0 | GCLK_CLKCTRL_ID(GCM_TC4_TC5)) ;
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while (GCLK->STATUS.bit.SYNCBUSY);
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timerReset(); //reset TC5
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// Set Timer counter 5 Mode to 16 bits, it will become a 16bit counter ('mode1' in the datasheet)
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_MODE_COUNT16;
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// Set TC5 waveform generation mode to 'match frequency'
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_WAVEGEN_MFRQ;
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//set prescaler
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//the clock normally counts at the GCLK_TC frequency, but we can set it to divide that frequency to slow it down
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//you can use different prescaler divisons here like TC_CTRLA_PRESCALER_DIV1 to get a different range
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_PRESCALER_DIV1024 | TC_CTRLA_ENABLE; //it will divide GCLK_TC frequency by 1024
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//set the compare-capture register.
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//The counter will count up to this value (it's a 16bit counter so we use uint16_t)
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//this is how we fine-tune the frequency, make it count to a lower or higher value
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//system clock should be 1MHz (8MHz/8) at Reset by default
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TC5->COUNT16.CC[0].reg = (uint16_t) (SystemCoreClock / sampleRate);
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while (timerIsSyncing());
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// Configure interrupt request
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NVIC_DisableIRQ(TC5_IRQn);
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NVIC_ClearPendingIRQ(TC5_IRQn);
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NVIC_SetPriority(TC5_IRQn, 0);
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NVIC_EnableIRQ(TC5_IRQn);
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// Enable the TC5 interrupt request
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TC5->COUNT16.INTENSET.bit.MC0 = 1;
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while (timerIsSyncing()); //wait until TC5 is done syncing
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}
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//Function that is used to check if TC5 is done syncing
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//returns true when it is done syncing
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bool timerIsSyncing() {
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return TC5->COUNT16.STATUS.reg & TC_STATUS_SYNCBUSY;
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}
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//This function enables TC5 and waits for it to be ready
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void timerStartCounter() {
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TC5->COUNT16.CTRLA.reg |= TC_CTRLA_ENABLE; //set the CTRLA register
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while (timerIsSyncing()); //wait until snyc'd
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}
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//Reset TC5
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void timerReset() {
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TC5->COUNT16.CTRLA.reg = TC_CTRLA_SWRST;
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while (timerIsSyncing());
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while (TC5->COUNT16.CTRLA.bit.SWRST);
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}
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//disable TC5
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void timerDisable() {
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TC5->COUNT16.CTRLA.reg &= ~TC_CTRLA_ENABLE;
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while (timerIsSyncing());
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}
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