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|
//go:build stm32f4 || stm32f1
package machine
// I2C implementation for 'older' STM32 MCUs, including the F1 and F4 series
// of MCUs.
import (
"device/stm32"
"unsafe"
)
const (
flagOVR = 0x00010800
flagAF = 0x00010400
flagARLO = 0x00010200
flagBERR = 0x00010100
flagTXE = 0x00010080
flagRXNE = 0x00010040
flagSTOPF = 0x00010010
flagADD10 = 0x00010008
flagBTF = 0x00010004
flagADDR = 0x00010002
flagSB = 0x00010001
flagDUALF = 0x00100080
flagGENCALL = 0x00100010
flagTRA = 0x00100004
flagBUSY = 0x00100002
flagMSL = 0x00100001
)
func (i2c *I2C) hasFlag(flag uint32) bool {
const mask = 0x0000FFFF
if uint8(flag>>16) == 1 {
return i2c.Bus.SR1.HasBits(flag & mask)
} else {
return i2c.Bus.SR2.HasBits(flag & mask)
}
}
func (i2c *I2C) clearFlag(flag uint32) {
const mask = 0x0000FFFF
i2c.Bus.SR1.Set(^(flag & mask))
}
// clearFlagADDR reads both status registers to clear any pending ADDR flags.
func (i2c *I2C) clearFlagADDR() {
i2c.Bus.SR1.Get()
i2c.Bus.SR2.Get()
}
func (i2c *I2C) waitForFlag(flag uint32, set bool) bool {
const tryMax = 10000
hasFlag := false
for i := 0; !hasFlag && i < tryMax; i++ {
hasFlag = i2c.hasFlag(flag) == set
}
return hasFlag
}
func (i2c *I2C) waitForFlagOrError(flag uint32, set bool) bool {
const tryMax = 10000
hasFlag := false
for i := 0; !hasFlag && i < tryMax; i++ {
if hasFlag = i2c.hasFlag(flag) == set; !hasFlag {
// check for ACK failure
if i2c.hasFlag(flagAF) {
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
// clear pending flags
i2c.clearFlag(flagAF)
return false
} else if i2c.hasFlag(flagSTOPF) {
// clear stop flag
i2c.clearFlag(flagSTOPF)
return false
}
}
}
return hasFlag
}
type transferOption uint32
const (
frameFirst = 0x00000001
frameFirstAndNext = 0x00000002
frameNext = 0x00000004
frameFirstAndLast = 0x00000008
frameLastNoStop = 0x00000010
frameLast = 0x00000020
frameNoOption = 0xFFFF0000
)
// I2C fast mode (Fm) duty cycle
const (
DutyCycle2 = 0
DutyCycle16x9 = 1
)
// I2CConfig is used to store config info for I2C.
type I2CConfig struct {
Frequency uint32
SCL Pin
SDA Pin
DutyCycle uint8
}
// Configure is intended to setup the STM32 I2C interface.
func (i2c *I2C) Configure(config I2CConfig) error {
// The following is the required sequence in controller mode.
// 1. Program the peripheral input clock in I2C_CR2 Register in order to
// generate correct timings
// 2. Configure the clock control registers
// 3. Configure the rise time register
// 4. Program the I2C_CR1 register to enable the peripheral
// 5. Set the START bit in the I2C_CR1 register to generate a Start condition
// disable I2C interface before any configuration changes
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_PE)
// reset I2C bus
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_SWRST)
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_SWRST)
// enable clock for I2C
enableAltFuncClock(unsafe.Pointer(i2c.Bus))
// init pins
if config.SCL == 0 && config.SDA == 0 {
config.SCL = I2C0_SCL_PIN
config.SDA = I2C0_SDA_PIN
}
i2c.configurePins(config)
// default to 100 kHz (Sm, standard mode) if no frequency is set
if config.Frequency == 0 {
config.Frequency = 100 * KHz
}
// configure I2C input clock
i2c.Bus.CR2.SetBits(i2c.getFreqRange(config))
// configure rise time
i2c.Bus.TRISE.Set(i2c.getRiseTime(config))
// configure clock control
i2c.Bus.CCR.Set(i2c.getSpeed(config))
// disable GeneralCall and NoStretch modes
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ENGC | stm32.I2C_CR1_NOSTRETCH)
// enable I2C interface
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_PE)
return nil
}
// SetBaudRate sets the communication speed for I2C.
func (i2c *I2C) SetBaudRate(br uint32) error {
// TODO: implement
return errI2CNotImplemented
}
func (i2c *I2C) Tx(addr uint16, w, r []byte) error {
if err := i2c.controllerTransmit(addr, w); nil != err {
return err
}
if len(r) > 0 {
if err := i2c.controllerReceive(addr, r); nil != err {
return err
}
}
return nil
}
func (i2c *I2C) controllerTransmit(addr uint16, w []byte) error {
if !i2c.waitForFlag(flagBUSY, false) {
return errI2CBusReadyTimeout
}
// disable POS
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_POS)
pos := 0
rem := len(w)
// send peripheral address
if err := i2c.controllerRequestWrite(addr, frameNoOption); nil != err {
return err
}
// clear ADDR flag
i2c.clearFlagADDR()
for rem > 0 {
// wait for TXE flag set
if !i2c.waitForFlagOrError(flagTXE, true) {
return errI2CAckExpected
}
// write data to DR
i2c.Bus.DR.Set(uint32(w[pos]))
// update counters
pos++
rem--
if i2c.hasFlag(flagBTF) && rem != 0 {
// write data to DR
i2c.Bus.DR.Set(uint32(w[pos]))
// update counters
pos++
rem--
}
// wait for transfer finished flag BTF set
if !i2c.waitForFlagOrError(flagBTF, true) {
return errI2CWriteTimeout
}
}
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
return nil
}
func (i2c *I2C) controllerRequestWrite(addr uint16, option transferOption) error {
if frameFirstAndLast == option || frameFirst == option || frameNoOption == option {
// generate start condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_START)
} else if false /* (hi2c->PreviousState == I2C_STATE_MASTER_BUSY_RX) */ {
// generate restart condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_START)
}
// ensure start bit is set
if !i2c.waitForFlag(flagSB, true) {
return errI2CSignalStartTimeout
}
// send peripheral address
i2c.Bus.DR.Set(uint32(addr) << 1)
// wait for address ACK from peripheral
if !i2c.waitForFlagOrError(flagADDR, true) {
return errI2CSignalStartTimeout
}
return nil
}
func (i2c *I2C) controllerReceive(addr uint16, r []byte) error {
if !i2c.waitForFlag(flagBUSY, false) {
return errI2CBusReadyTimeout
}
// disable POS
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_POS)
pos := 0
rem := len(r)
// send peripheral address
if err := i2c.controllerRequestRead(addr, frameNoOption); nil != err {
return err
}
switch rem {
case 0:
// clear ADDR flag
i2c.clearFlagADDR()
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
case 1:
// disable ACK
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
// clear ADDR flag
i2c.clearFlagADDR()
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
case 2:
// disable ACK
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
// enable POS
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_POS)
// clear ADDR flag
i2c.clearFlagADDR()
default:
// enable ACK
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
// clear ADDR flag
i2c.clearFlagADDR()
}
for rem > 0 {
switch rem {
case 1:
// wait until RXNE flag is set
if !i2c.waitForFlagOrError(flagRXNE, true) {
return errI2CReadTimeout
}
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
case 2:
// wait until transfer finished flag BTF is set
if !i2c.waitForFlag(flagBTF, true) {
return errI2CReadTimeout
}
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
case 3:
// wait until transfer finished flag BTF is set
if !i2c.waitForFlag(flagBTF, true) {
return errI2CReadTimeout
}
// disable ACK
i2c.Bus.CR1.ClearBits(stm32.I2C_CR1_ACK)
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
// wait until transfer finished flag BTF is set
if !i2c.waitForFlag(flagBTF, true) {
return errI2CReadTimeout
}
// generate stop condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_STOP)
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
default:
// wait until RXNE flag is set
if !i2c.waitForFlagOrError(flagRXNE, true) {
return errI2CReadTimeout
}
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
if i2c.hasFlag(flagBTF) {
// read data from DR
r[pos] = byte(i2c.Bus.DR.Get())
// update counters
pos++
rem--
}
}
}
return nil
}
func (i2c *I2C) controllerRequestRead(addr uint16, option transferOption) error {
// enable ACK
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_ACK)
if frameFirstAndLast == option || frameFirst == option || frameNoOption == option {
// generate start condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_START)
} else if false /* (hi2c->PreviousState == I2C_STATE_MASTER_BUSY_TX) */ {
// generate restart condition
i2c.Bus.CR1.SetBits(stm32.I2C_CR1_START)
}
// ensure start bit is set
if !i2c.waitForFlag(flagSB, true) {
return errI2CSignalStartTimeout
}
// send peripheral address
i2c.Bus.DR.Set(uint32(addr)<<1 | 1)
// wait for address ACK from peripheral
if !i2c.waitForFlagOrError(flagADDR, true) {
return errI2CSignalStartTimeout
}
return nil
}
|
