stm32 add SPI for stm32f4

src/device/stm32/stm32-moder-bitfields.go

@@ -43,3 +43,15 @@ const (
 	GPIOPUPDRPullUp   = 1
 	GPIOPUPDRPullDown = 2
 )
+
+// SPI prescaler values fPCLK / X
+const (
+	SPI_PCLK_2   = 0
+	SPI_PCLK_4   = 1
+	SPI_PCLK_8   = 2
+	SPI_PCLK_16  = 3
+	SPI_PCLK_32  = 4
+	SPI_PCLK_64  = 5
+	SPI_PCLK_128 = 6
+	SPI_PCLK_256 = 7
+)

src/machine/board_stm32f4disco.go

@@ -129,3 +129,30 @@ var (
 func init() {
 	UART0.Interrupt = interrupt.New(stm32.IRQ_USART2, UART0.handleInterrupt)
 }
+
+// SPI pins
+const (
+	SPI1_SCK_PIN  = PA5
+	SPI1_MISO_PIN = PA6
+	SPI1_MOSI_PIN = PA7
+	SPI0_SCK_PIN  = SPI1_SCK_PIN
+	SPI0_MISO_PIN = SPI1_MISO_PIN
+	SPI0_MOSI_PIN = SPI1_MOSI_PIN
+)
+
+// MEMs accelerometer
+const (
+	MEMS_ACCEL_CS   = PE3
+	MEMS_ACCEL_INT1 = PE0
+	MEMS_ACCEL_INT2 = PE1
+)
+
+// Since the first interface is named SPI1, both SPI0 and SPI1 refer to SPI1.
+// TODO: implement SPI2 and SPI3.
+var (
+	SPI0 = SPI{
+		Bus:             stm32.SPI1,
+		AltFuncSelector: stm32.AF5_SPI1_SPI2,
+	}
+	SPI1 = &SPI0
+)

src/machine/machine_stm32_spi.go

@@ -0,0 +1,99 @@
+// +build stm32
+
+package machine
+
+// Peripheral abstraction layer for SPI on the stm32 family
+
+import (
+	"device/stm32"
+	"unsafe"
+)
+
+// SPIConfig is used to store config info for SPI.
+type SPIConfig struct {
+	Frequency uint32
+	SCK       Pin
+	MOSI      Pin
+	MISO      Pin
+	LSBFirst  bool
+	Mode      uint8
+}
+
+// Configure is intended to setup the STM32 SPI1 interface.
+// Features still TODO:
+// - support SPI2 and SPI3
+// - allow setting data size to 16 bits?
+// - allow setting direction in HW for additional optimization?
+// - hardware SS pin?
+func (spi SPI) Configure(config SPIConfig) {
+	// enable clock for SPI
+	enableAltFuncClock(unsafe.Pointer(spi.Bus))
+
+	// Get SPI baud rate based on the bus speed it's attached to
+	var conf uint32 = spi.getBaudRate(config)
+
+	// set bit transfer order
+	if config.LSBFirst {
+		conf |= stm32.SPI_CR1_LSBFIRST
+	}
+
+	// set polarity and phase on the SPI interface
+	switch config.Mode {
+	case Mode0:
+		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
+		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
+	case Mode1:
+		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
+		conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
+	case Mode2:
+		conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
+		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
+	case Mode3:
+		conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
+		conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
+	default: // to mode 0
+		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
+		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
+	}
+
+	// set to SPI master
+	conf |= stm32.SPI_CR1_MSTR
+
+	// disable MCU acting as SPI slave
+	conf |= stm32.SPI_CR1_SSM | stm32.SPI_CR1_SSI
+
+	// now set the configuration
+	spi.Bus.CR1.Set(conf)
+
+	// init pins
+	if config.SCK == 0 && config.MOSI == 0 && config.MISO == 0 {
+		config.SCK = SPI0_SCK_PIN
+		config.MOSI = SPI0_MOSI_PIN
+		config.MISO = SPI0_MISO_PIN
+	}
+	spi.configurePins(config)
+
+	// enable SPI interface
+	spi.Bus.CR1.SetBits(stm32.SPI_CR1_SPE)
+}
+
+// Transfer writes/reads a single byte using the SPI interface.
+func (spi SPI) Transfer(w byte) (byte, error) {
+	// Write data to be transmitted to the SPI data register
+	spi.Bus.DR.Set(uint32(w))
+
+	// Wait until transmit complete
+	for !spi.Bus.SR.HasBits(stm32.SPI_SR_TXE) {
+	}
+
+	// Wait until receive complete
+	for !spi.Bus.SR.HasBits(stm32.SPI_SR_RXNE) {
+	}
+
+	// Wait until SPI is not busy
+	for spi.Bus.SR.HasBits(stm32.SPI_SR_BSY) {
+	}
+
+	// Return received data from SPI data register
+	return byte(spi.Bus.DR.Get()), nil
+}

src/machine/machine_stm32f103xx.go

@@ -148,7 +148,8 @@ func (uart UART) getBaudRateDivisor(br uint32) uint32 {
 	return divider
 }
 
-// SPI on the STM32.
+//---------- SPI related types and code
+
 type SPI struct {
 	Bus *stm32.SPI_Type
 }
@@ -161,26 +162,8 @@ var (
 	SPI0 = SPI1
 )
 
-// SPIConfig is used to store config info for SPI.
+// Set baud rate for SPI
-type SPIConfig struct {
+func (spi SPI) getBaudRate(config SPIConfig) uint32 {
-	Frequency uint32
-	SCK       Pin
-	MOSI      Pin
-	MISO      Pin
-	LSBFirst  bool
-	Mode      uint8
-}
-
-// Configure is intended to setup the STM32 SPI1 interface.
-// Features still TODO:
-// - support SPI2 and SPI3
-// - allow setting data size to 16 bits?
-// - allow setting direction in HW for additional optimization?
-// - hardware SS pin?
-func (spi SPI) Configure(config SPIConfig) {
-	// enable clock for SPI
-	stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_SPI1EN)
-
 	var conf uint32
 
 	// set frequency dependent on PCLK2 prescaler (div 1)
@@ -203,82 +186,18 @@ func (spi SPI) Configure(config SPIConfig) {
 	default:
 		conf |= stm32.SPI_BaudRatePrescaler_256
 	}
-
+	return conf
-	// set bit transfer order
-	if config.LSBFirst {
-		conf |= stm32.SPI_FirstBit_LSB
-	}
-
-	// set mode
-	switch config.Mode {
-	case 0:
-		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
-		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
-	case 1:
-		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
-		conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
-	case 2:
-		conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
-		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
-	case 3:
-		conf |= (1 << stm32.SPI_CR1_CPOL_Pos)
-		conf |= (1 << stm32.SPI_CR1_CPHA_Pos)
-	default: // to mode 0
-		conf &^= (1 << stm32.SPI_CR1_CPOL_Pos)
-		conf &^= (1 << stm32.SPI_CR1_CPHA_Pos)
-	}
-
-	// set to SPI master
-	conf |= stm32.SPI_Mode_Master
-
-	// now set the configuration
-	spi.Bus.CR1.Set(conf)
-
-	// init pins
-	spi.setPins(config.SCK, config.MOSI, config.MISO)
-
-	// enable SPI interface
-	spi.Bus.CR1.SetBits(stm32.SPI_CR1_SPE)
 }
 
-// Transfer writes/reads a single byte using the SPI interface.
+// Configure SPI pins for input output and clock
-func (spi SPI) Transfer(w byte) (byte, error) {
+func (spi SPI) configurePins(config SPIConfig) {
-	// Write data to be transmitted to the SPI data register
+	config.SCK.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
-	spi.Bus.DR.Set(uint32(w))
+	config.MOSI.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
-
+	config.MISO.Configure(PinConfig{Mode: PinInputModeFloating})
-	// Wait until transmit complete
-	for !spi.Bus.SR.HasBits(stm32.SPI_SR_TXE) {
-	}
-
-	// Wait until receive complete
-	for !spi.Bus.SR.HasBits(stm32.SPI_SR_RXNE) {
-	}
-
-	// Wait until SPI is not busy
-	for spi.Bus.SR.HasBits(stm32.SPI_SR_BSY) {
-	}
-
-	// Return received data from SPI data register
-	return byte(spi.Bus.DR.Get()), nil
 }
 
-func (spi SPI) setPins(sck, mosi, miso Pin) {
+//---------- I2C related types and code
-	if sck == 0 {
-		sck = SPI0_SCK_PIN
-	}
-	if mosi == 0 {
-		mosi = SPI0_MOSI_PIN
-	}
-	if miso == 0 {
-		miso = SPI0_MISO_PIN
-	}
 
-	sck.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
-	mosi.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltPushPull})
-	miso.Configure(PinConfig{Mode: PinInputModeFloating})
-}
-
-// I2C on the STM32F103xx.
 type I2C struct {
 	Bus *stm32.I2C_Type
 }

src/machine/machine_stm32f407.go

@@ -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)
+}

src/machine/spi.go

@@ -1,9 +1,17 @@
-// +build !baremetal sam stm32,!stm32f407 fe310
+// +build !baremetal sam stm32 fe310
 
 package machine
 
 import "errors"
 
+// SPI phase and polarity configs CPOL and CPHA
+const (
+	Mode0 = 0
+	Mode1 = 1
+	Mode2 = 2
+	Mode3 = 3
+)
+
 var (
 	ErrTxInvalidSliceSize = errors.New("SPI write and read slices must be same size")
 )