83 строки
2 КиБ
Go
83 строки
2 КиБ
Go
// +build stm32
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package machine
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// Peripheral abstraction layer for UARTs on the stm32 family.
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import (
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"device/stm32"
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"runtime/interrupt"
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"runtime/volatile"
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"unsafe"
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)
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// UART representation
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type UART struct {
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Buffer *RingBuffer
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Bus *stm32.USART_Type
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Interrupt interrupt.Interrupt
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TxAltFuncSelector uint8
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RxAltFuncSelector uint8
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// Registers specific to the chip
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rxReg *volatile.Register32
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txReg *volatile.Register32
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statusReg *volatile.Register32
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txEmptyFlag uint32
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}
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// Configure the UART.
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func (uart *UART) Configure(config UARTConfig) {
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// Default baud rate to 115200.
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if config.BaudRate == 0 {
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config.BaudRate = 115200
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}
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// Set the GPIO pins to defaults if they're not set
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if config.TX == 0 && config.RX == 0 {
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config.TX = UART_TX_PIN
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config.RX = UART_RX_PIN
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}
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// STM32 families have different, but compatible, registers for
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// basic UART functions. For each family populate the registers
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// into `uart`.
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uart.setRegisters()
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// Enable USART clock
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enableAltFuncClock(unsafe.Pointer(uart.Bus))
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uart.configurePins(config)
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// Set baud rate
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uart.SetBaudRate(config.BaudRate)
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// Enable USART port, tx, rx and rx interrupts
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uart.Bus.CR1.Set(stm32.USART_CR1_TE | stm32.USART_CR1_RE | stm32.USART_CR1_RXNEIE | stm32.USART_CR1_UE)
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// Enable RX IRQ
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uart.Interrupt.SetPriority(0xc0)
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uart.Interrupt.Enable()
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}
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// handleInterrupt should be called from the appropriate interrupt handler for
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// this UART instance.
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func (uart *UART) handleInterrupt(interrupt.Interrupt) {
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uart.Receive(byte((uart.rxReg.Get() & 0xFF)))
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}
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// SetBaudRate sets the communication speed for the UART. Defer to chip-specific
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// routines for calculation
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func (uart *UART) SetBaudRate(br uint32) {
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divider := uart.getBaudRateDivisor(br)
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uart.Bus.BRR.Set(divider)
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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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uart.txReg.Set(uint32(c))
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for !uart.statusReg.HasBits(uart.txEmptyFlag) {
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}
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return nil
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}
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