da505a6b17
All the AVRs that I've looked at had the same pin/port structure, with the possible states being input/floating, input/pullup, low, and high (with the same PORT/DDR registers). The main difference is the number of available ports and pins. To reduce the amount of code and avoid duplication (and thus errors) I decided to centralize this, following the design used by the atmega2560 but while using a trick to save tracking a few registers. In the process, I noticed that the Pin.Get() function was incorrect on the atmega2560 implementation. It is now fixed in the unified code.
90 строки
2,5 КиБ
Go
90 строки
2,5 КиБ
Go
// +build avr,atmega328p
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package machine
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import (
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"device/avr"
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"runtime/volatile"
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)
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const irq_USART0_RX = avr.IRQ_USART_RX
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// getPortMask returns the PORTx register and mask for the pin.
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func (p Pin) getPortMask() (*volatile.Register8, uint8) {
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switch {
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case p >= PB0 && p <= PB7: // port B
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return avr.PORTB, 1 << uint8(p-portB)
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case p >= PC0 && p <= PC7: // port C
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return avr.PORTC, 1 << uint8(p-portC)
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default: // port D
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return avr.PORTD, 1 << uint8(p-portD)
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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.SetBits(avr.TCCR0A_WGM00)
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// set timer 0 prescale factor to 64
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avr.TCCR0B.SetBits(avr.TCCR0B_CS01 | avr.TCCR0B_CS00)
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// set timer 1 prescale factor to 64
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avr.TCCR1B.SetBits(avr.TCCR1B_CS11)
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// put timer 1 in 8-bit phase correct pwm mode
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avr.TCCR1A.SetBits(avr.TCCR1A_WGM10)
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// set timer 2 prescale factor to 64
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avr.TCCR2B.SetBits(avr.TCCR2B_CS22)
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// configure timer 2 for phase correct pwm (8-bit)
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avr.TCCR2A.SetBits(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() error {
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switch pwm.Pin / 8 {
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case 0: // port B
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avr.DDRB.SetBits(1 << uint8(pwm.Pin))
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case 2: // port D
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avr.DDRD.SetBits(1 << uint8(pwm.Pin-16))
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}
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return nil
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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 := uint8(value >> 8)
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switch pwm.Pin {
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case PD3:
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// connect pwm to pin on timer 2, channel B
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avr.TCCR2A.SetBits(avr.TCCR2A_COM2B1)
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avr.OCR2B.Set(value8) // set pwm duty
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case PD5:
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// connect pwm to pin on timer 0, channel B
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avr.TCCR0A.SetBits(avr.TCCR0A_COM0B1)
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avr.OCR0B.Set(value8) // set pwm duty
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case PD6:
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// connect pwm to pin on timer 0, channel A
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avr.TCCR0A.SetBits(avr.TCCR0A_COM0A1)
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avr.OCR0A.Set(value8) // set pwm duty
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case PB1:
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// connect pwm to pin on timer 1, channel A
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avr.TCCR1A.SetBits(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.Set(value8) // set pwm duty
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case PB2:
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// connect pwm to pin on timer 1, channel B
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avr.TCCR1A.SetBits(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.Set(value8) // set pwm duty
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case PB3:
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// connect pwm to pin on timer 2, channel A
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avr.TCCR2A.SetBits(avr.TCCR2A_COM2A1)
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avr.OCR2A.Set(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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