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stm32 add SPI for stm32f4

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This commit is contained in:
GeoffThomas
2020-03-22 10:28:47 -05:00
committed by Ron Evans
parent ac73430502
commit b4dddfe439
6 changed files with 217 additions and 93 deletions
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src/machine/machine_stm32f407.go
+59
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@@ -108,3 +108,62 @@ func (uart UART) getBaudRateDivisor(baudRate uint32) uint32 {
}
return clock / baudRate
}
//---------- SPI related types and code
// SPI on the STM32Fxxx using MODER / alternate function pins
type SPI struct {
Bus *stm32.SPI_Type
AltFuncSelector stm32.AltFunc
}
// Set baud rate for SPI
func (spi SPI) getBaudRate(config SPIConfig) uint32 {
var conf uint32
localFrequency := config.Frequency
if spi.Bus != stm32.SPI1 {
// Assume it's SPI2 or SPI3 on APB1 at 1/2 the clock frequency of APB2, so
// we want to pretend to request 2x the baudrate asked for
localFrequency = localFrequency * 2
}
// set frequency dependent on PCLK prescaler. Since these are rather weird
// speeds due to the CPU freqency, pick a range up to that frquency for
// clients to use more human-understandable numbers, e.g. nearest 100KHz
// These are based on APB2 clock frquency (84MHz on the discovery board)
// TODO: also include the MCU/APB clock setting in the equation
switch true {
case localFrequency < 328125:
conf = stm32.SPI_PCLK_256
case localFrequency < 656250:
conf = stm32.SPI_PCLK_128
case localFrequency < 1312500:
conf = stm32.SPI_PCLK_64
case localFrequency < 2625000:
conf = stm32.SPI_PCLK_32
case localFrequency < 5250000:
conf = stm32.SPI_PCLK_16
case localFrequency < 10500000:
conf = stm32.SPI_PCLK_8
// NOTE: many SPI components won't operate reliably (or at all) above 10MHz
// Check the datasheet of the part
case localFrequency < 21000000:
conf = stm32.SPI_PCLK_4
case localFrequency < 42000000:
conf = stm32.SPI_PCLK_2
default:
// None of the specific baudrates were selected; choose the lowest speed
conf = stm32.SPI_PCLK_256
}
return conf << stm32.SPI_CR1_BR_Pos
}
// Configure SPI pins for input output and clock
func (spi SPI) configurePins(config SPIConfig) {
config.SCK.ConfigureAltFunc(PinConfig{Mode: PinModeSPICLK}, spi.AltFuncSelector)
config.MOSI.ConfigureAltFunc(PinConfig{Mode: PinModeSPIMOSI}, spi.AltFuncSelector)
config.MISO.ConfigureAltFunc(PinConfig{Mode: PinModeSPIMISO}, spi.AltFuncSelector)
}