machine/stm32f103xx: support for SPI interface
Signed-off-by: Ron Evans <ron@hybridgroup.com>
Этот коммит содержится в:
Ron Evans
Ayke van Laethem
родитель
f71e1bcf03
коммит
dccfae485c
5 изменённых файлов: 176 добавлений и 5 удалений
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@ -58,4 +58,31 @@ const (
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RCC_RTCCLKSource_LSE = 0x00000100
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RCC_RTCCLKSource_LSI = 0x00000200
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RCC_RTCCLKSource_HSE_Div128 = 0x00000300
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// SPI settings
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SPI_FirstBit_MSB = 0x0000
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SPI_FirstBit_LSB = 0x0080
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SPI_BaudRatePrescaler_2 = 0x0000
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SPI_BaudRatePrescaler_4 = 0x0008
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SPI_BaudRatePrescaler_8 = 0x0010
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SPI_BaudRatePrescaler_16 = 0x0018
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SPI_BaudRatePrescaler_32 = 0x0020
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SPI_BaudRatePrescaler_64 = 0x0028
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SPI_BaudRatePrescaler_128 = 0x0030
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SPI_BaudRatePrescaler_256 = 0x0038
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SPI_Direction_2Lines_FullDuplex = 0x0000
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SPI_Direction_2Lines_RxOnly = 0x0400
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SPI_Direction_1Line_Rx = 0x8000
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SPI_Direction_1Line_Tx = 0xC000
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SPI_Mode_Master = 0x0104
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SPI_Mode_Slave = 0x0000
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SPI_NSS_Soft = 0x0200
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SPI_NSS_Hard = 0x0000
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SPI_NSSInternalSoft_Set = 0x0100
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SPI_NSSInternalSoft_Reset = 0xFEFF
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)
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@ -44,3 +44,16 @@ const (
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const (
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LED = PC13
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)
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// UART pins
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const (
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UART_TX_PIN = PA9
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UART_RX_PIN = PA10
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)
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// SPI pins
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const (
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SPI0_SCK_PIN = PA5
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SPI0_MOSI_PIN = PA7
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SPI0_MISO_PIN = PA6
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)
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@ -123,8 +123,8 @@ func (uart UART) Configure(config UARTConfig) {
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GPIO{PB7}.Configure(GPIOConfig{Mode: GPIO_INPUT_MODE_FLOATING})
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default:
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// use standard TX/RX pins PA9 and PA10
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GPIO{PA9}.Configure(GPIOConfig{Mode: GPIO_OUTPUT_50MHz + GPIO_OUTPUT_MODE_ALT_PUSH_PULL})
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GPIO{PA10}.Configure(GPIOConfig{Mode: GPIO_INPUT_MODE_FLOATING})
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GPIO{UART_TX_PIN}.Configure(GPIOConfig{Mode: GPIO_OUTPUT_50MHz + GPIO_OUTPUT_MODE_ALT_PUSH_PULL})
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GPIO{UART_RX_PIN}.Configure(GPIOConfig{Mode: GPIO_INPUT_MODE_FLOATING})
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}
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// Enable USART1 clock
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@ -143,7 +143,8 @@ func (uart UART) Configure(config UARTConfig) {
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// SetBaudRate sets the communication speed for the UART.
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func (uart UART) SetBaudRate(br uint32) {
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divider := CPU_FREQUENCY / br
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// first divide by PCK2 prescaler (div 4) and then desired baudrate
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divider := CPU_FREQUENCY / 4 / br
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stm32.USART1.BRR = stm32.RegValue(divider)
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}
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@ -160,3 +161,132 @@ func (uart UART) WriteByte(c byte) error {
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func handleUART1() {
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bufferPut(byte((stm32.USART1.DR & 0xFF)))
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}
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// SPI on the STM32.
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type SPI struct {
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Bus *stm32.SPI_Type
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}
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// There are 3 SPI interfaces on the STM32F103xx.
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// Since the first interface is named SPI1, both SPI0 and SPI1 refer to SPI1.
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// TODO: implement SPI2 and SPI3.
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var (
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SPI1 = SPI{Bus: stm32.SPI1}
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SPI0 = SPI1
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)
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// SPIConfig is used to store config info for SPI.
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type SPIConfig struct {
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Frequency uint32
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SCK uint8
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MOSI uint8
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MISO uint8
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LSBFirst bool
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Mode uint8
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}
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// Configure is intended to setup the STM32 SPI1 interface.
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// Features still TODO:
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// - support SPI2 and SPI3
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// - allow setting data size to 16 bits?
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// - allow setting direction in HW for additional optimization?
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// - hardware SS pin?
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func (spi SPI) Configure(config SPIConfig) {
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// enable clock for SPI
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stm32.RCC.APB2ENR |= stm32.RCC_APB2ENR_SPI1EN
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var conf uint16
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// set frequency
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switch config.Frequency {
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case 125000:
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conf |= stm32.SPI_BaudRatePrescaler_128
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case 250000:
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conf |= stm32.SPI_BaudRatePrescaler_64
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case 500000:
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conf |= stm32.SPI_BaudRatePrescaler_32
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case 1000000:
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conf |= stm32.SPI_BaudRatePrescaler_16
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case 2000000:
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conf |= stm32.SPI_BaudRatePrescaler_8
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case 4000000:
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conf |= stm32.SPI_BaudRatePrescaler_4
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case 8000000:
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conf |= stm32.SPI_BaudRatePrescaler_2
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default:
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conf |= stm32.SPI_BaudRatePrescaler_128
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}
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// set bit transfer order
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if config.LSBFirst {
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conf |= stm32.SPI_FirstBit_LSB
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}
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// set mode
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switch config.Mode {
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case 0:
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conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
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conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
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case 1:
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conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
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conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
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case 2:
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conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
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conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
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case 3:
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conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
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conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
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default: // to mode 0
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conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
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conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
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}
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// set to SPI master
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conf |= stm32.SPI_Mode_Master
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// now set the configuration
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spi.Bus.CR1 = stm32.RegValue(conf)
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// init pins
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spi.setPins(config.SCK, config.MOSI, config.MISO)
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// enable SPI interface
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spi.Bus.CR1 |= stm32.SPI_CR1_SPE
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}
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// Transfer writes/reads a single byte using the SPI interface.
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func (spi SPI) Transfer(w byte) (byte, error) {
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// Write data to be transmitted to the SPI data register
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spi.Bus.DR = stm32.RegValue(w)
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// Wait until transmit complete
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for (spi.Bus.SR & stm32.SPI_SR_TXE) == 0 {
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}
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// Wait until receive complete
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for (spi.Bus.SR & stm32.SPI_SR_RXNE) == 0 {
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}
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// Wait until SPI is not busy
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for (spi.Bus.SR & stm32.SPI_SR_BSY) > 0 {
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}
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// Return received data from SPI data register
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return byte(spi.Bus.DR), nil
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}
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func (spi SPI) setPins(sck, mosi, miso uint8) {
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if sck == 0 {
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sck = SPI0_SCK_PIN
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}
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if mosi == 0 {
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mosi = SPI0_MOSI_PIN
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}
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if miso == 0 {
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miso = SPI0_MISO_PIN
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}
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GPIO{sck}.Configure(GPIOConfig{Mode: GPIO_OUTPUT_50MHz + GPIO_OUTPUT_MODE_ALT_PUSH_PULL})
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GPIO{mosi}.Configure(GPIOConfig{Mode: GPIO_OUTPUT_50MHz + GPIO_OUTPUT_MODE_ALT_PUSH_PULL})
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GPIO{miso}.Configure(GPIOConfig{Mode: GPIO_INPUT_MODE_FLOATING})
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}
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@ -1,4 +1,4 @@
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// +build nrf
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// +build nrf stm32f103xx
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package machine
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@ -22,7 +22,8 @@ func putchar(c byte) {
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// initCLK sets clock to 72MHz using HSE 8MHz crystal w/ PLL X 9 (8MHz x 9 = 72MHz).
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func initCLK() {
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stm32.FLASH.ACR |= stm32.FLASH_ACR_LATENCY_2 // Two wait states, per datasheet
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stm32.RCC.CFGR |= stm32.RCC_CFGR_PPRE1_DIV_2 // prescale AHB1 = HCLK/2
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stm32.RCC.CFGR |= stm32.RCC_CFGR_PPRE1_DIV_2 // prescale PCLK1 = HCLK/2
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stm32.RCC.CFGR |= stm32.RCC_CFGR_PPRE2_DIV_4 // prescale PCLK2 = HCLK/4
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stm32.RCC.CR |= stm32.RCC_CR_HSEON // enable HSE clock
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// wait for the HSEREADY flag
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