mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-08-05 03:27:48 +00:00
Johann Freymuth
413 lines
11 KiB
Go
413 lines
11 KiB
Go
//go:build esp32
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package machine
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import (
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"device/esp"
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"runtime/volatile"
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"unsafe"
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)
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var (
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I2C0 = &I2C{Bus: esp.I2C0, funcSCL: 29, funcSDA: 30}
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I2C1 = &I2C{Bus: esp.I2C1, funcSCL: 95, funcSDA: 96}
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)
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type I2C struct {
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Bus *esp.I2C_Type
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funcSCL, funcSDA uint32
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config I2CConfig
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}
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// I2CConfig is used to store config info for I2C.
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type I2CConfig struct {
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Frequency uint32 // in Hz
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SCL Pin
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SDA Pin
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}
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const (
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i2cClkSourceFrequency = uint32(80 * MHz)
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)
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func (i2c *I2C) Configure(config I2CConfig) error {
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if config.Frequency == 0 {
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config.Frequency = 400 * KHz
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}
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if config.SCL == 0 {
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config.SCL = SCL_PIN
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}
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if config.SDA == 0 {
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config.SDA = SDA_PIN
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}
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i2c.config = config
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i2c.initAll()
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return nil
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}
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func (i2c *I2C) initAll() {
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i2c.initClock()
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i2c.initNoiseFilter()
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i2c.initPins()
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i2c.initFrequency()
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i2c.startMaster()
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}
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//go:inline
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func (i2c *I2C) initClock() {
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// reset I2C clock
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if i2c.Bus == esp.I2C0 {
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esp.DPORT.SetPERIP_RST_EN_I2C0_EXT0_RST(1)
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esp.DPORT.SetPERIP_CLK_EN_I2C0_EXT0_CLK_EN(1)
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esp.DPORT.SetPERIP_RST_EN_I2C0_EXT0_RST(0)
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} else {
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esp.DPORT.SetPERIP_RST_EN_I2C_EXT1_RST(1)
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esp.DPORT.SetPERIP_CLK_EN_I2C_EXT1_CLK_EN(1)
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esp.DPORT.SetPERIP_RST_EN_I2C_EXT1_RST(0)
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}
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// disable interrupts
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i2c.Bus.INT_ENA.Set(0)
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i2c.Bus.INT_CLR.Set(0x3fff)
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i2c.Bus.SetCTR_CLK_EN(1)
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}
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//go:inline
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func (i2c *I2C) initNoiseFilter() {
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i2c.Bus.SCL_FILTER_CFG.Set(0xF)
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i2c.Bus.SDA_FILTER_CFG.Set(0xF)
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}
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//go:inline
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func (i2c *I2C) initPins() {
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var muxConfig uint32
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const function = 2 // function 2 is just GPIO
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// SDA
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muxConfig = function << esp.IO_MUX_GPIO0_MCU_SEL_Pos
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// Make this pin an input pin (always).
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muxConfig |= esp.IO_MUX_GPIO0_FUN_IE
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// Set drive strength: 0 is lowest, 3 is highest.
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muxConfig |= 1 << esp.IO_MUX_GPIO0_FUN_DRV_Pos
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i2c.config.SDA.mux().Set(muxConfig)
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i2c.config.SDA.outFunc().Set(i2c.funcSDA)
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inFunc(i2c.funcSDA).Set(uint32(esp.GPIO_FUNC_IN_SEL_CFG_SEL | i2c.config.SDA))
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i2c.config.SDA.Set(true)
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// Configure the pad with the given IO mux configuration.
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i2c.config.SDA.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
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esp.GPIO.ENABLE_W1TS.Set(1 << int(i2c.config.SDA))
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i2c.Bus.SetCTR_SDA_FORCE_OUT(1)
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// SCL
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muxConfig = function << esp.IO_MUX_GPIO0_MCU_SEL_Pos
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// Make this pin an input pin (always).
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muxConfig |= esp.IO_MUX_GPIO0_FUN_IE
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// Set drive strength: 0 is lowest, 3 is highest.
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muxConfig |= 1 << esp.IO_MUX_GPIO0_FUN_DRV_Pos
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i2c.config.SCL.mux().Set(muxConfig)
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i2c.config.SCL.outFunc().Set(i2c.funcSCL)
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inFunc(i2c.funcSCL).Set(uint32(esp.GPIO_FUNC_IN_SEL_CFG_SEL | i2c.config.SCL))
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i2c.config.SCL.Set(true)
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// Configure the pad with the given IO mux configuration.
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i2c.config.SCL.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
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esp.GPIO.ENABLE_W1TS.Set(1 << int(i2c.config.SCL))
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i2c.Bus.SetCTR_SCL_FORCE_OUT(1)
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}
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//go:inline
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func (i2c *I2C) initFrequency() {
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clkmDiv := i2cClkSourceFrequency/(i2c.config.Frequency*1024) + 1
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sclkFreq := i2cClkSourceFrequency / clkmDiv
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halfCycle := sclkFreq / i2c.config.Frequency / 2
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//SCL
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sclLow := halfCycle
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sclWaitHigh := uint32(0)
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if i2c.config.Frequency > 50000 {
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sclWaitHigh = halfCycle / 8 // compensate the time when freq > 50K
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}
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sclHigh := halfCycle - sclWaitHigh
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// SDA
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sdaHold := halfCycle / 4
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sda_sample := halfCycle / 2
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setup := halfCycle
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hold := halfCycle
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i2c.Bus.SetSCL_LOW_PERIOD(sclLow - 1)
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i2c.Bus.SetSCL_HIGH_PERIOD(sclHigh)
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i2c.Bus.SetSCL_RSTART_SETUP_TIME(setup)
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i2c.Bus.SetSCL_STOP_SETUP_TIME(setup)
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i2c.Bus.SetSCL_START_HOLD_TIME(hold - 1)
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i2c.Bus.SetSCL_STOP_HOLD_TIME(hold - 1)
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i2c.Bus.SetSDA_SAMPLE_TIME(sda_sample)
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i2c.Bus.SetSDA_HOLD_TIME(sdaHold)
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// set timeout value
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i2c.Bus.SetTO_TIME_OUT(20 * halfCycle)
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}
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//go:inline
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func (i2c *I2C) startMaster() {
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// FIFO mode for data
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i2c.Bus.SetFIFO_CONF_NONFIFO_EN(0)
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// Reset TX & RX buffers
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i2c.Bus.SetFIFO_CONF_RX_FIFO_RST(1)
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i2c.Bus.SetFIFO_CONF_RX_FIFO_RST(0)
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i2c.Bus.SetFIFO_CONF_TX_FIFO_RST(1)
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i2c.Bus.SetFIFO_CONF_TX_FIFO_RST(0)
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// enable master mode
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i2c.Bus.SetCTR_MS_MODE(1)
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}
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func (i2c *I2C) resetBus() {
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// unlike esp32c3, the esp32 i2c modules do not have a reset fsm register,
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// so we need to:
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// 1. disconnect the pins
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// 2. generate a stop condition manually
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// 3. do a full reset
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// 4. redo all configuration
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i2c.config.SDA.mux().Set(2<<esp.IO_MUX_GPIO0_MCU_SEL_Pos | esp.IO_MUX_GPIO0_FUN_IE | 1<<esp.IO_MUX_GPIO0_FUN_DRV_Pos)
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i2c.config.SDA.outFunc().Set(0x500)
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i2c.config.SDA.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
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i2c.config.SCL.mux().Set(2<<esp.IO_MUX_GPIO0_MCU_SEL_Pos | esp.IO_MUX_GPIO0_FUN_IE | 1<<esp.IO_MUX_GPIO0_FUN_DRV_Pos)
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i2c.config.SCL.outFunc().Set(0x500)
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i2c.config.SCL.pinReg().SetBits(esp.GPIO_PIN_PAD_DRIVER)
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// bit-bang a read-NACK in case any device on the bus is in the middle of a write
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i2c.config.SCL.Low()
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i2c.config.SDA.High()
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wait()
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for i := 0; i < 9; i++ {
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if i2c.config.SDA.Get() {
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break
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}
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i2c.config.SCL.High()
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wait()
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i2c.config.SCL.Low()
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wait()
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}
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i2c.config.SDA.Low()
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i2c.config.SCL.High()
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wait()
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i2c.config.SDA.High()
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// initAll contains initClock which contains a reset
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i2c.initAll()
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}
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func wait() {
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end := nanotime() + 5_000
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for nanotime() < end {
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//spin
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}
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}
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type i2cCommandType = uint32
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type i2cAck = uint32
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const (
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i2cCMD_RSTART i2cCommandType = 0 << 11
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i2cCMD_WRITE i2cCommandType = 1<<11 | 1<<8 // WRITE + ack_check_en
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i2cCMD_READ i2cCommandType = 2 << 11
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i2cCMD_READLAST i2cCommandType = 2<<11 | 1<<10 // READ + NACK
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i2cCMD_STOP i2cCommandType = 3 << 11
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i2cCMD_END i2cCommandType = 4 << 11
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)
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type i2cCommand struct {
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cmd i2cCommandType
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data []byte
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head int
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}
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//go:linkname nanotime runtime.nanotime
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func nanotime() int64
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func (i2c *I2C) transmit(addr uint16, cmd []i2cCommand, timeoutMS int) error {
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if i2c.Bus.GetSR_BUS_BUSY() == 1 {
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i2c.resetBus()
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}
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const intMask = esp.I2C_INT_STATUS_END_DETECT_INT_ST_Msk | esp.I2C_INT_STATUS_TRANS_COMPLETE_INT_ST_Msk | esp.I2C_INT_STATUS_TIME_OUT_INT_ST_Msk | esp.I2C_INT_STATUS_ACK_ERR_INT_ST_Msk | esp.I2C_INT_STATUS_ARBITRATION_LOST_INT_ST_Msk
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i2c.Bus.INT_CLR.Set(intMask)
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i2c.Bus.INT_ENA.Set(intMask)
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defer func() {
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i2c.Bus.INT_CLR.Set(intMask)
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i2c.Bus.INT_ENA.Set(0)
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}()
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timeoutNS := int64(timeoutMS) * 1000000
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needAddress := true
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needRestart := false
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readLast := false
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var readTo []byte
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for cmdIdx, reg := 0, &i2c.Bus.COMD0; cmdIdx < len(cmd); {
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c := &cmd[cmdIdx]
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switch c.cmd {
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case i2cCMD_RSTART:
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reg.Set(i2cCMD_RSTART)
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reg = nextAddress(reg)
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cmdIdx++
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case i2cCMD_WRITE:
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count := 32
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if needAddress {
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needAddress = false
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i2c.Bus.SetDATA_FIFO_RDATA((uint32(addr) & 0x7f) << 1)
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count--
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i2c.Bus.SLAVE_ADDR.Set(uint32(addr))
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}
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for ; count > 0 && c.head < len(c.data); count, c.head = count-1, c.head+1 {
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i2c.Bus.SetDATA_FIFO_RDATA(uint32(c.data[c.head]))
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}
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reg.Set(i2cCMD_WRITE | uint32(32-count))
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reg = nextAddress(reg)
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if c.head < len(c.data) {
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reg.Set(i2cCMD_END)
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reg = nil
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} else {
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cmdIdx++
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}
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needRestart = true
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case i2cCMD_READ:
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if needAddress {
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needAddress = false
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i2c.Bus.SetDATA_FIFO_RDATA((uint32(addr)&0x7f)<<1 | 1)
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i2c.Bus.SLAVE_ADDR.Set(uint32(addr))
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reg.Set(i2cCMD_WRITE | 1)
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reg = nextAddress(reg)
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}
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if needRestart {
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// We need to send RESTART again after i2cCMD_WRITE.
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reg.Set(i2cCMD_RSTART)
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reg = nextAddress(reg)
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reg.Set(i2cCMD_WRITE | 1)
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reg = nextAddress(reg)
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i2c.Bus.SetDATA_FIFO_RDATA((uint32(addr)&0x7f)<<1 | 1)
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needRestart = false
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}
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count := 32
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bytes := len(c.data) - c.head
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// Only last byte in sequence must be sent with ACK set to 1 to indicate end of data.
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split := bytes <= count
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if split {
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bytes--
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}
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if bytes > 32 {
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bytes = 32
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}
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if bytes > 0 {
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reg.Set(i2cCMD_READ | uint32(bytes))
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reg = nextAddress(reg)
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}
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if split {
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readLast = true
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reg.Set(i2cCMD_READLAST | 1)
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reg = nextAddress(reg)
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readTo = c.data[c.head : c.head+bytes+1] // read bytes + 1 last byte
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cmdIdx++
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} else {
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reg.Set(i2cCMD_END)
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readTo = c.data[c.head : c.head+bytes]
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reg = nil
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}
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case i2cCMD_STOP:
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reg.Set(i2cCMD_STOP)
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reg = nil
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cmdIdx++
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}
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if reg == nil {
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// transmit now
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i2c.Bus.SetCTR_TRANS_START(1)
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end := nanotime() + timeoutNS
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var mask uint32
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for mask = i2c.Bus.INT_STATUS.Get(); mask&intMask == 0; mask = i2c.Bus.INT_STATUS.Get() {
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if nanotime() > end {
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// timeout leaves the bus in an undefined state, reset
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i2c.resetBus()
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if readTo != nil {
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return errI2CReadTimeout
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}
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return errI2CWriteTimeout
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}
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}
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switch {
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case mask&esp.I2C_INT_STATUS_ACK_ERR_INT_ST_Msk != 0 && !readLast:
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return errI2CAckExpected
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case mask&esp.I2C_INT_STATUS_TIME_OUT_INT_ST_Msk != 0:
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// timeout leaves the bus in an undefined state, reset
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i2c.resetBus()
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if readTo != nil {
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return errI2CReadTimeout
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}
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return errI2CWriteTimeout
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}
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i2c.Bus.INT_CLR.SetBits(intMask)
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for i := 0; i < len(readTo); i++ {
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readTo[i] = byte(i2c.Bus.GetDATA_FIFO_RDATA() & 0xff)
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c.head++
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}
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readTo = nil
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reg = &i2c.Bus.COMD0
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}
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}
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return nil
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}
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// Tx does a single I2C transaction at the specified address.
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// It clocks out the given address, writes the bytes in w, reads back len(r)
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// bytes and stores them in r, and generates a stop condition on the bus.
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func (i2c *I2C) Tx(addr uint16, w, r []byte) (err error) {
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// timeout in microseconds.
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const timeout = 40 // 40ms is a reasonable time for a real-time system.
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cmd := make([]i2cCommand, 0, 8)
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cmd = append(cmd, i2cCommand{cmd: i2cCMD_RSTART})
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if len(w) > 0 {
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cmd = append(cmd, i2cCommand{cmd: i2cCMD_WRITE, data: w})
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}
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if len(r) > 0 {
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cmd = append(cmd, i2cCommand{cmd: i2cCMD_READ, data: r})
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}
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cmd = append(cmd, i2cCommand{cmd: i2cCMD_STOP})
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return i2c.transmit(addr, cmd, timeout)
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}
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func (i2c *I2C) SetBaudRate(br uint32) error {
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return errI2CNotImplemented
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}
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func (p Pin) pinReg() *volatile.Register32 {
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return (*volatile.Register32)(unsafe.Pointer((uintptr(unsafe.Pointer(&esp.GPIO.PIN0)) + uintptr(p)*4)))
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}
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func nextAddress(reg *volatile.Register32) *volatile.Register32 {
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return (*volatile.Register32)(unsafe.Add(unsafe.Pointer(reg), 4))
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}
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// CheckDevice does an empty I2C transaction at the specified address.
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// This can be used to find out if any device with that address is
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// connected, e.g. for enumerating all devices on the bus.
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func (i2c *I2C) CheckDevice(addr uint16) bool {
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// timeout in microseconds.
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const timeout = 40 // 40ms is a reasonable time for a real-time system.
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cmd := []i2cCommand{
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{cmd: i2cCMD_RSTART},
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{cmd: i2cCMD_WRITE},
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{cmd: i2cCMD_STOP},
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}
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return i2c.transmit(addr, cmd, timeout) == nil
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}
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