stm32: move f103 (bluepill) to common i2c code

4 files changed, 46 insertions, 428 deletions

diff --git a/src/machine/board_bluepill.go b/src/machine/board_bluepill.go
index e3055eec4..51e389349 100644
--- a/src/machine/board_bluepill.go
+++ b/src/machine/board_bluepill.go
@@ -85,6 +85,6 @@ const (
 
 // I2C pins
 const (
-	SDA_PIN = PB7
-	SCL_PIN = PB6
+	I2C0_SDA_PIN = PB7
+	I2C0_SCL_PIN = PB6
 )
diff --git a/src/machine/board_nucleof103rb.go b/src/machine/board_nucleof103rb.go
index f3be4d7f7..8908864d8 100644
--- a/src/machine/board_nucleof103rb.go
+++ b/src/machine/board_nucleof103rb.go
@@ -120,6 +120,6 @@ const (
 
 // I2C pins
 const (
-	SCL_PIN = PB6
-	SDA_PIN = PB7
+	I2C0_SCL_PIN = PB6
+	I2C0_SDA_PIN = PB7
 )
diff --git a/src/machine/machine_stm32_i2c.go b/src/machine/machine_stm32_i2c.go
index fbee11d8e..4642b3fc2 100644
--- a/src/machine/machine_stm32_i2c.go
+++ b/src/machine/machine_stm32_i2c.go
@@ -1,4 +1,4 @@
-// +build stm32,!stm32f103,!stm32f7x2,!stm32l5x2,!stm32l0
+// +build stm32,!stm32f7x2,!stm32l5x2,!stm32l0
 
 package machine
 
diff --git a/src/machine/machine_stm32f103.go b/src/machine/machine_stm32f103.go
index 2de299c58..ae8113e72 100644
--- a/src/machine/machine_stm32f103.go
+++ b/src/machine/machine_stm32f103.go
@@ -197,10 +197,6 @@ func (spi SPI) configurePins(config SPIConfig) {
 
 //---------- I2C related types and code
 
-type I2C struct {
-	Bus *stm32.I2C_Type
-}
-
 // There are 2 I2C interfaces on the STM32F103xx.
 // Since the first interface is named I2C1, both I2C0 and I2C1 refer to I2C1.
 // TODO: implement I2C2.
@@ -209,451 +205,73 @@ var (
 	I2C0 = I2C1
 )
 
-// I2CConfig is used to store config info for I2C.
-type I2CConfig struct {
-	Frequency uint32
-	SCL       Pin
-	SDA       Pin
+type I2C struct {
+	Bus *stm32.I2C_Type
 }
 
-// Configure is intended to setup the I2C interface.
-func (i2c I2C) Configure(config I2CConfig) error {
-	// Default I2C bus speed is 100 kHz.
-	if config.Frequency == 0 {
-		config.Frequency = TWI_FREQ_100KHZ
-	}
-
-	// enable clock for I2C
-	stm32.RCC.APB1ENR.SetBits(stm32.RCC_APB1ENR_I2C1EN)
-
-	// I2C1 pins
-	switch config.SDA {
-	case PB9:
-		config.SCL = PB8
+func (i2c I2C) configurePins(config I2CConfig) {
+	if config.SDA == PB9 {
 		// use alternate I2C1 pins PB8/PB9 via AFIO mapping
 		stm32.RCC.APB2ENR.SetBits(stm32.RCC_APB2ENR_AFIOEN)
 		stm32.AFIO.MAPR.SetBits(stm32.AFIO_MAPR_I2C1_REMAP)
-	default:
-		// use default I2C1 pins PB6/PB7
-		config.SDA = SDA_PIN
-		config.SCL = SCL_PIN
 	}
 
 	config.SDA.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltOpenDrain})
 	config.SCL.Configure(PinConfig{Mode: PinOutput50MHz + PinOutputModeAltOpenDrain})
+}
 
-	// Disable the selected I2C peripheral to configure
-	i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_PE)
-
+func (i2c I2C) getFreqRange(config I2CConfig) uint32 {
 	// pclk1 clock speed is main frequency divided by PCLK1 prescaler (div 2)
 	pclk1 := CPUFrequency() / 2
 
 	// set freqency range to PCLK1 clock speed in MHz
 	// aka setting the value 36 means to use 36 MHz clock
-	pclk1Mhz := pclk1 / 1000000
-	i2c.Bus.CR2.SetBits(pclk1Mhz)
-
-	switch config.Frequency {
-	case TWI_FREQ_100KHZ:
-		// Normal mode speed calculation
-		ccr := pclk1 / (config.Frequency * 2)
-		i2c.Bus.CCR.Set(ccr)
-
-		// duty cycle 2
-		i2c.Bus.CCR.ClearBits(stm32.I2C_CCR_DUTY)
-
-		// frequency standard mode
-		i2c.Bus.CCR.ClearBits(stm32.I2C_CCR_F_S)
-
-		// Set Maximum Rise Time for standard mode
-		i2c.Bus.TRISE.Set(pclk1Mhz)
-
-	case TWI_FREQ_400KHZ:
-		// Fast mode speed calculation
-		ccr := pclk1 / (config.Frequency * 3)
-		i2c.Bus.CCR.Set(ccr)
-
-		// duty cycle 2
-		i2c.Bus.CCR.ClearBits(stm32.I2C_CCR_DUTY)
-
-		// frequency fast mode
-		i2c.Bus.CCR.SetBits(stm32.I2C_CCR_F_S)
-
-		// Set Maximum Rise Time for fast mode
-		i2c.Bus.TRISE.Set(((pclk1Mhz * 300) / 1000))
-	}
-
-	// re-enable the selected I2C peripheral
-	i2c.Bus.CR1.SetBits(stm32.I2C_CR1_PE)
-
-	return nil
+	return pclk1 / 1000000
 }
 
-// Tx does a single I2C transaction at the specified address.
-// It clocks out the given address, writes the bytes in w, reads back len(r)
-// bytes and stores them in r, and generates a stop condition on the bus.
-func (i2c I2C) Tx(addr uint16, w, r []byte) error {
-	var err error
-	if len(w) != 0 {
-		// start transmission for writing
-		err = i2c.signalStart()
-		if err != nil {
-			return err
-		}
-
-		// send address
-		err = i2c.sendAddress(uint8(addr), true)
-		if err != nil {
-			return err
-		}
-
-		for _, b := range w {
-			err = i2c.WriteByte(b)
-			if err != nil {
-				return err
-			}
-		}
-
-		// sending stop here for write
-		err = i2c.signalStop()
-		if err != nil {
-			return err
-		}
+func (i2c I2C) getRiseTime(config I2CConfig) uint32 {
+	// These bits must be programmed with the maximum SCL rise time given in the
+	// I2C bus specification, incremented by 1.
+	// For instance: in Sm mode, the maximum allowed SCL rise time is 1000 ns.
+	// If, in the I2C_CR2 register, the value of FREQ[5:0] bits is equal to 0x08
+	// and PCLK1 = 125 ns, therefore the TRISE[5:0] bits must be programmed with
+	// 09h (1000 ns / 125 ns = 8 + 1)
+	freqRange := i2c.getFreqRange(config)
+	if config.Frequency > 100000 {
+		// fast mode (Fm) adjustment
+		freqRange *= 300
+		freqRange /= 1000
 	}
-	if len(r) != 0 {
-		// re-start transmission for reading
-		err = i2c.signalStart()
-		if err != nil {
-			return err
-		}
-
-		// 1 byte
-		switch len(r) {
-		case 1:
-			// send address
-			err = i2c.sendAddress(uint8(addr), false)
-			if err != nil {
-				return err
-			}
-
-			// Disable ACK of received data
-			i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
-
-			// clear timeout here
-			timeout := i2cTimeout
-			for !i2c.Bus.SR2.HasBits(stm32.I2C_SR2_MSL | stm32.I2C_SR2_BUSY) {
-				timeout--
-				if timeout == 0 {
-					return errI2CWriteTimeout
-				}
-			}
-
-			// Generate stop condition
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
-
-			timeout = i2cTimeout
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_RxNE) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// Read and return data byte from I2C data register
-			r[0] = byte(i2c.Bus.DR.Get())
-
-			// wait for stop
-			return i2c.waitForStop()
-
-		case 2:
-			// enable pos
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_POS)
-
-			// Enable ACK of received data
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
-
-			// send address
-			err = i2c.sendAddress(uint8(addr), false)
-			if err != nil {
-				return err
-			}
-
-			// clear address here
-			timeout := i2cTimeout
-			for !i2c.Bus.SR2.HasBits(stm32.I2C_SR2_MSL | stm32.I2C_SR2_BUSY) {
-				timeout--
-				if timeout == 0 {
-					return errI2CWriteTimeout
-				}
-			}
-
-			// Disable ACK of received data
-			i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
-
-			// wait for btf. we need a longer timeout here than normal.
-			timeout = 1000
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_BTF) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// Generate stop condition
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
-
-			// read the 2 bytes by reading twice.
-			r[0] = byte(i2c.Bus.DR.Get())
-			r[1] = byte(i2c.Bus.DR.Get())
-
-			// wait for stop
-			err = i2c.waitForStop()
-
-			//disable pos
-			i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_POS)
-
-			return err
-
-		case 3:
-			// Enable ACK of received data
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
-
-			// send address
-			err = i2c.sendAddress(uint8(addr), false)
-			if err != nil {
-				return err
-			}
-
-			// clear address here
-			timeout := i2cTimeout
-			for !i2c.Bus.SR2.HasBits(stm32.I2C_SR2_MSL | stm32.I2C_SR2_BUSY) {
-				timeout--
-				if timeout == 0 {
-					return errI2CWriteTimeout
-				}
-			}
-
-			// Enable ACK of received data
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
-
-			// wait for btf. we need a longer timeout here than normal.
-			timeout = 1000
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_BTF) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// Disable ACK of received data
-			i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
-
-			// read the first byte
-			r[0] = byte(i2c.Bus.DR.Get())
-
-			timeout = 1000
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_BTF) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// Generate stop condition
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
-
-			// read the last 2 bytes by reading twice.
-			r[1] = byte(i2c.Bus.DR.Get())
-			r[2] = byte(i2c.Bus.DR.Get())
-
-			// wait for stop
-			return i2c.waitForStop()
-
-		default:
-			// more than 3 bytes of data to read
-
-			// send address
-			err = i2c.sendAddress(uint8(addr), false)
-			if err != nil {
-				return err
-			}
-
-			// clear address here
-			timeout := i2cTimeout
-			for !i2c.Bus.SR2.HasBits(stm32.I2C_SR2_MSL | stm32.I2C_SR2_BUSY) {
-				timeout--
-				if timeout == 0 {
-					return errI2CWriteTimeout
-				}
-			}
-
-			for i := 0; i < len(r)-3; i++ {
-				// Enable ACK of received data
-				i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
-
-				// wait for btf. we need a longer timeout here than normal.
-				timeout = 1000
-				for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_BTF) {
-					timeout--
-					if timeout == 0 {
-						return errI2CReadTimeout
-					}
-				}
-
-				// read the next byte
-				r[i] = byte(i2c.Bus.DR.Get())
-			}
-
-			// wait for btf. we need a longer timeout here than normal.
-			timeout = 1000
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_BTF) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// Disable ACK of received data
-			i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
-
-			// get third from last byte
-			r[len(r)-3] = byte(i2c.Bus.DR.Get())
-
-			// Generate stop condition
-			i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
-
-			// get second from last byte
-			r[len(r)-2] = byte(i2c.Bus.DR.Get())
-
-			timeout = i2cTimeout
-			for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_RxNE) {
-				timeout--
-				if timeout == 0 {
-					return errI2CReadTimeout
-				}
-			}
-
-			// get last byte
-			r[len(r)-1] = byte(i2c.Bus.DR.Get())
-
-			// wait for stop
-			return i2c.waitForStop()
-		}
-	}
-
-	return nil
+	return (freqRange + 1) << stm32.I2C_TRISE_TRISE_Pos
 }
 
-const i2cTimeout = 1000
-
-// signalStart sends a start signal.
-func (i2c I2C) signalStart() error {
-	// Wait until I2C is not busy
-	timeout := i2cTimeout
-	for i2c.Bus.SR2.HasBits(stm32.I2C_SR2_BUSY) {
-		timeout--
-		if timeout == 0 {
-			return errI2CSignalStartTimeout
-		}
+func (i2c I2C) getSpeed(config I2CConfig) uint32 {
+	ccr := func(pclk uint32, freq uint32, coeff uint32) uint32 {
+		return (((pclk - 1) / (freq * coeff)) + 1) & stm32.I2C_CCR_CCR_Msk
 	}
-
-	// clear stop
-	i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_STOP)
-
-	// Generate start condition
-	i2c.Bus.CR1.SetBits(stm32.I2C_CR1_START)
-
-	// Wait for I2C EV5 aka SB flag.
-	timeout = i2cTimeout
-	for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_SB) {
-		timeout--
-		if timeout == 0 {
-			return errI2CSignalStartTimeout
+	sm := func(pclk uint32, freq uint32) uint32 { // standard mode (Sm)
+		if s := ccr(pclk, freq, 2); s < 4 {
+			return 4
+		} else {
+			return s
 		}
 	}
-
-	return nil
-}
-
-// signalStop sends a stop signal and waits for it to succeed.
-func (i2c I2C) signalStop() error {
-	// Generate stop condition
-	i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
-
-	// wait for stop
-	return i2c.waitForStop()
-}
-
-// waitForStop waits after a stop signal.
-func (i2c I2C) waitForStop() error {
-	// Wait until I2C is stopped
-	timeout := i2cTimeout
-	for i2c.Bus.SR1.HasBits(stm32.I2C_SR1_STOPF) {
-		timeout--
-		if timeout == 0 {
-			return errI2CSignalStopTimeout
+	fm := func(pclk uint32, freq uint32, duty uint8) uint32 { // fast mode (Fm)
+		if duty == DutyCycle2 {
+			return ccr(pclk, freq, 3)
+		} else {
+			return ccr(pclk, freq, 25) | stm32.I2C_CCR_DUTY
 		}
 	}
-
-	return nil
-}
-
-// Send address of device we want to talk to
-func (i2c I2C) sendAddress(address uint8, write bool) error {
-	data := (address << 1)
-	if !write {
-		data |= 1 // set read flag
-	}
-
-	i2c.Bus.DR.Set(uint32(data))
-
-	// Wait for I2C EV6 event.
-	// Destination device acknowledges address
-	timeout := i2cTimeout
-	if write {
-		// EV6 which is ADDR flag.
-		for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_ADDR) {
-			timeout--
-			if timeout == 0 {
-				return errI2CWriteTimeout
-			}
-		}
-
-		timeout = i2cTimeout
-		for !i2c.Bus.SR2.HasBits(stm32.I2C_SR2_MSL | stm32.I2C_SR2_BUSY | stm32.I2C_SR2_TRA) {
-			timeout--
-			if timeout == 0 {
-				return errI2CWriteTimeout
-			}
-		}
+	clock := CPUFrequency() / 2
+	if config.Frequency <= 100000 {
+		return sm(clock, config.Frequency)
 	} else {
-		// I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED which is ADDR flag.
-		for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_ADDR) {
-			timeout--
-			if timeout == 0 {
-				return errI2CWriteTimeout
-			}
+		s := fm(clock, config.Frequency, config.DutyCycle)
+		if (s & stm32.I2C_CCR_CCR_Msk) == 0 {
+			return 1
+		} else {
+			return s | stm32.I2C_CCR_F_S
 		}
 	}
-
-	return nil
-}
-
-// WriteByte writes a single byte to the I2C bus.
-func (i2c I2C) WriteByte(data byte) error {
-	// Send data byte
-	i2c.Bus.DR.Set(uint32(data))
-
-	// Wait for I2C EV8_2 when data has been physically shifted out and
-	// output on the bus.
-	// I2C_EVENT_MASTER_BYTE_TRANSMITTED is TXE flag.
-	timeout := i2cTimeout
-	for !i2c.Bus.SR1.HasBits(stm32.I2C_SR1_TxE) {
-		timeout--
-		if timeout == 0 {
-			return errI2CWriteTimeout
-		}
-	}
-
-	return nil
 }