4f4d7976c6
* machine/uart: add core support for multiple UARTs by allowing for multiple RingBuffers * machine/uart: complete core support for multiple UARTs * machine/uart: no need to store pointer to UART, better to treat like I2C and SPI * machine/uart: increase ring buffer size to 128 bytes * machine/uart: improve godocs comments and use comma-ok idiom for buffer Put/Get methods
258 строки
6,8 КиБ
Go
258 строки
6,8 КиБ
Go
// +build avr,atmega
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package machine
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import (
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"device/avr"
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)
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// Configure sets the pin to input or output.
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func (p GPIO) Configure(config GPIOConfig) {
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if config.Mode == GPIO_OUTPUT { // set output bit
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if p.Pin < 8 {
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*avr.DDRD |= 1 << p.Pin
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} else {
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*avr.DDRB |= 1 << (p.Pin - 8)
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}
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} else { // configure input: clear output bit
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if p.Pin < 8 {
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*avr.DDRD &^= 1 << p.Pin
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} else {
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*avr.DDRB &^= 1 << (p.Pin - 8)
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}
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}
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}
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// Get returns the current value of a GPIO pin.
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func (p GPIO) Get() bool {
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if p.Pin < 8 {
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val := *avr.PIND & (1 << p.Pin)
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return (val > 0)
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} else {
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val := *avr.PINB & (1 << (p.Pin - 8))
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return (val > 0)
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}
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}
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func (p GPIO) getPortMask() (*avr.RegValue, uint8) {
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if p.Pin < 8 {
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return avr.PORTD, 1 << p.Pin
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} else {
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return avr.PORTB, 1 << (p.Pin - 8)
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}
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}
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// InitPWM initializes the registers needed for PWM.
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func InitPWM() {
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// use waveform generation
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*avr.TCCR0A |= avr.TCCR0A_WGM00
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// set timer 0 prescale factor to 64
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*avr.TCCR0B |= avr.TCCR0B_CS01 | avr.TCCR0B_CS00
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// set timer 1 prescale factor to 64
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*avr.TCCR1B |= avr.TCCR1B_CS11
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// put timer 1 in 8-bit phase correct pwm mode
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*avr.TCCR1A |= avr.TCCR1A_WGM10
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// set timer 2 prescale factor to 64
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*avr.TCCR2B |= avr.TCCR2B_CS22
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// configure timer 2 for phase correct pwm (8-bit)
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*avr.TCCR2A |= avr.TCCR2A_WGM20
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}
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// Configure configures a PWM pin for output.
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func (pwm PWM) Configure() {
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if pwm.Pin < 8 {
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*avr.DDRD |= 1 << pwm.Pin
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} else {
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*avr.DDRB |= 1 << (pwm.Pin - 8)
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}
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}
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// Set turns on the duty cycle for a PWM pin using the provided value. On the AVR this is normally a
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// 8-bit value ranging from 0 to 255.
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func (pwm PWM) Set(value uint16) {
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value8 := value >> 8
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switch pwm.Pin {
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case 3:
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// connect pwm to pin on timer 2, channel B
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*avr.TCCR2A |= avr.TCCR2A_COM2B1
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*avr.OCR2B = avr.RegValue(value8) // set pwm duty
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case 5:
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// connect pwm to pin on timer 0, channel B
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*avr.TCCR0A |= avr.TCCR0A_COM0B1
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*avr.OCR0B = avr.RegValue(value8) // set pwm duty
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case 6:
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// connect pwm to pin on timer 0, channel A
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*avr.TCCR0A |= avr.TCCR0A_COM0A1
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*avr.OCR0A = avr.RegValue(value8) // set pwm duty
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case 9:
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// connect pwm to pin on timer 1, channel A
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*avr.TCCR1A |= avr.TCCR1A_COM1A1
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// this is a 16-bit value, but we only currently allow the low order bits to be set
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*avr.OCR1AL = avr.RegValue(value8) // set pwm duty
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case 10:
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// connect pwm to pin on timer 1, channel B
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*avr.TCCR1A |= avr.TCCR1A_COM1B1
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// this is a 16-bit value, but we only currently allow the low order bits to be set
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*avr.OCR1BL = avr.RegValue(value8) // set pwm duty
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case 11:
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// connect pwm to pin on timer 2, channel A
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*avr.TCCR2A |= avr.TCCR2A_COM2A1
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*avr.OCR2A = avr.RegValue(value8) // set pwm duty
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default:
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panic("Invalid PWM pin")
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}
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}
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// I2CConfig is used to store config info for I2C.
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type I2CConfig struct {
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Frequency uint32
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}
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// Configure is intended to setup the I2C interface.
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func (i2c I2C) Configure(config I2CConfig) {
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// Default I2C bus speed is 100 kHz.
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if config.Frequency == 0 {
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config.Frequency = TWI_FREQ_100KHZ
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}
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// Activate internal pullups for twi.
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*avr.PORTC |= (avr.DIDR0_ADC4D | avr.DIDR0_ADC5D)
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// Initialize twi prescaler and bit rate.
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*avr.TWSR |= (avr.TWSR_TWPS0 | avr.TWSR_TWPS1)
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// twi bit rate formula from atmega128 manual pg. 204:
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// SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
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// NOTE: TWBR should be 10 or higher for master mode.
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// It is 72 for a 16mhz board with 100kHz TWI
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*avr.TWBR = avr.RegValue(((CPU_FREQUENCY / config.Frequency) - 16) / 2)
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// Enable twi module.
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*avr.TWCR = avr.TWCR_TWEN
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}
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// Tx does a single I2C transaction at the specified address.
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// It clocks out the given address, writes the bytes in w, reads back len(r)
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// bytes and stores them in r, and generates a stop condition on the bus.
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func (i2c I2C) Tx(addr uint16, w, r []byte) error {
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if len(w) != 0 {
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i2c.start(uint8(addr), true) // start transmission for writing
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for _, b := range w {
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i2c.writeByte(b)
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}
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}
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if len(r) != 0 {
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i2c.start(uint8(addr), false) // re-start transmission for reading
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for i := range r { // read each char
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r[i] = i2c.readByte()
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}
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}
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if len(w) != 0 || len(r) != 0 {
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// Stop the transmission after it has been started.
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i2c.stop()
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}
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return nil
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}
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// start starts an I2C communication session.
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func (i2c I2C) start(address uint8, write bool) {
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// Clear TWI interrupt flag, put start condition on SDA, and enable TWI.
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*avr.TWCR = (avr.TWCR_TWINT | avr.TWCR_TWSTA | avr.TWCR_TWEN)
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// Wait till start condition is transmitted.
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for (*avr.TWCR & avr.TWCR_TWINT) == 0 {
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}
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// Write 7-bit shifted peripheral address.
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address <<= 1
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if !write {
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address |= 1 // set read flag
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}
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i2c.writeByte(address)
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}
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// stop ends an I2C communication session.
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func (i2c I2C) stop() {
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// Send stop condition.
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*avr.TWCR = (avr.TWCR_TWEN | avr.TWCR_TWINT | avr.TWCR_TWSTO)
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// Wait for stop condition to be executed on bus.
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for (*avr.TWCR & avr.TWCR_TWSTO) == 0 {
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}
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}
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// writeByte writes a single byte to the I2C bus.
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func (i2c I2C) writeByte(data byte) {
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// Write data to register.
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*avr.TWDR = avr.RegValue(data)
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// Clear TWI interrupt flag and enable TWI.
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*avr.TWCR = (avr.TWCR_TWEN | avr.TWCR_TWINT)
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// Wait till data is transmitted.
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for (*avr.TWCR & avr.TWCR_TWINT) == 0 {
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}
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}
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// readByte reads a single byte from the I2C bus.
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func (i2c I2C) readByte() byte {
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// Clear TWI interrupt flag and enable TWI.
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*avr.TWCR = (avr.TWCR_TWEN | avr.TWCR_TWINT | avr.TWCR_TWEA)
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// Wait till read request is transmitted.
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for (*avr.TWCR & avr.TWCR_TWINT) == 0 {
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}
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return byte(*avr.TWDR)
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}
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// UART on the AVR.
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type UART struct {
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Buffer *RingBuffer
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}
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// Configure the UART on the AVR. Defaults to 9600 baud on Arduino.
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func (uart UART) Configure(config UARTConfig) {
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if config.BaudRate == 0 {
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config.BaudRate = 9600
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}
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// Set baud rate based on prescale formula from
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// https://www.microchip.com/webdoc/AVRLibcReferenceManual/FAQ_1faq_wrong_baud_rate.html
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// ((F_CPU + UART_BAUD_RATE * 8L) / (UART_BAUD_RATE * 16L) - 1)
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ps := ((CPU_FREQUENCY+config.BaudRate*8)/(config.BaudRate*16) - 1)
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*avr.UBRR0H = avr.RegValue(ps >> 8)
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*avr.UBRR0L = avr.RegValue(ps & 0xff)
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// enable RX, TX and RX interrupt
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*avr.UCSR0B = avr.UCSR0B_RXEN0 | avr.UCSR0B_TXEN0 | avr.UCSR0B_RXCIE0
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// 8-bits data
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*avr.UCSR0C = avr.UCSR0C_UCSZ01 | avr.UCSR0C_UCSZ00
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}
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// WriteByte writes a byte of data to the UART.
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func (uart UART) WriteByte(c byte) error {
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// Wait until UART buffer is not busy.
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for (*avr.UCSR0A & avr.UCSR0A_UDRE0) == 0 {
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}
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*avr.UDR0 = avr.RegValue(c) // send char
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return nil
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}
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//go:interrupt USART_RX_vect
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func handleUSART_RX() {
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// Read register to clear it.
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data := *avr.UDR0
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// Ensure no error.
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if (*avr.UCSR0A & (avr.UCSR0A_FE0 | avr.UCSR0A_DOR0 | avr.UCSR0A_UPE0)) == 0 {
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// Put data from UDR register into buffer.
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UART0.Receive(byte(data))
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}
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}
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