/*
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* i2c_bitbang.c
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*
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* Created on: Jan 19, 2023
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* Author: Wenxue
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*/
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#include "i2c_bitbang.h"
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i2c_bus_t i2c_bus[I2CBUSMAX] =
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{
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/* Bus ChipAddr SCL_Pin SDA_Pin */
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{I2CBUS0, 0x00, {GPIOB, GPIO_PIN_6 }, {GPIOB, GPIO_PIN_7 } }, /* SHT20, RTC, OLED */
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{I2CBUS1, 0x00, {GPIOB, GPIO_PIN_10}, {GPIOB, GPIO_PIN_11} }, /* MikroBUS I2C interface */
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};
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enum
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{
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LOW,
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HIGH,
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};
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/*+--------------------------+
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*| Low level GPIO API |
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*+--------------------------+*/
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static inline void SDA_IN(uint8_t bus)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_bus[bus].sda.pin;
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GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
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GPIO_InitStruct.Pull = GPIO_PULLUP;
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
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HAL_GPIO_Init(i2c_bus[bus].sda.group, &GPIO_InitStruct);
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}
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static inline void SDA_OUT(uint8_t bus)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_bus[bus].sda.pin;
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GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
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GPIO_InitStruct.Pull = GPIO_PULLUP;
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
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HAL_GPIO_Init(i2c_bus[bus].sda.group, &GPIO_InitStruct);
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}
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static inline void SCL_OUT(uint8_t bus)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_bus[bus].scl.pin;
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GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
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GPIO_InitStruct.Pull = GPIO_PULLUP;
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GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
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HAL_GPIO_Init(i2c_bus[bus].scl.group, &GPIO_InitStruct);
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}
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static inline void SCL_SET(uint8_t bus, int level)
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{
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HAL_GPIO_WritePin(i2c_bus[bus].scl.group, i2c_bus[bus].scl.pin, level?GPIO_PIN_SET:GPIO_PIN_RESET);
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}
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static inline void SDA_SET(uint8_t bus, int level)
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{
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HAL_GPIO_WritePin(i2c_bus[bus].sda.group, i2c_bus[bus].sda.pin, level?GPIO_PIN_SET:GPIO_PIN_RESET);
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}
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static inline GPIO_PinState SCL_GET(uint8_t bus)
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{
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return HAL_GPIO_ReadPin(i2c_bus[bus].scl.group, i2c_bus[bus].scl.pin);
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}
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static inline GPIO_PinState SDA_GET(uint8_t bus)
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{
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return HAL_GPIO_ReadPin(i2c_bus[bus].sda.group, i2c_bus[bus].sda.pin);
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}
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/*+--------------------------+
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*| I2C Clock Sequence API |
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*+--------------------------+*/
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/* */
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#if 1
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#include "miscdev.h" /* delay_us() implement by TIM6 */
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#else
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static inline void delay_us(uint32_t us)
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{
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uint32_t i, j;
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for(j=0; j<450; j++)// 450 ~500
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for(i = 0; i < us; i++)
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{
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__NOP();
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}
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}
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#endif
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void I2C_StartCondition(uint8_t bus)
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{
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SDA_OUT(bus);
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SCL_OUT(bus);
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/* Start Condition Clock Sequence:
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______
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SCL: |___
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_____
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SDA: |_____
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*/
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SDA_SET(bus, HIGH);
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SCL_SET(bus, HIGH);
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delay_us(1);
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SDA_SET(bus, LOW);
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delay_us(1); // hold time start condition (t_HD;STA)
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SCL_SET(bus, LOW);
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delay_us(1);
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}
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void I2C_StopCondition(uint8_t bus)
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{
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SDA_OUT(bus);
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/* SCL Stop Condition Clock Sequence:
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_______
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SCL: ___|
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_____
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SDA: _____|
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*/
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SCL_SET(bus, LOW);
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SDA_SET(bus, LOW);
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delay_us(1);
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SCL_SET(bus, HIGH);
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SDA_SET(bus, HIGH);
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delay_us(1);
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}
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void I2C_Ack(uint8_t bus, uint8_t ack)
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{
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if(ACK_NONE == ack)
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return ;
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SCL_SET(bus, LOW);
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SDA_OUT(bus);
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if( ACK==ack )
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SDA_SET(bus, LOW);
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else if( NAK==ack )
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SDA_SET(bus, HIGH);
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delay_us(1);
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SCL_SET(bus, HIGH);
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delay_us(1);
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SCL_SET(bus, LOW);
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}
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uint8_t I2C_WriteByte(uint8_t bus, uint8_t txByte)
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{
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uint8_t error = NO_ERROR;
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uint8_t mask;
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SDA_OUT(bus);
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SCL_SET(bus, LOW);
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/* start send 8 bits data */
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for(mask=0x80; mask>0; mask>>=1)
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{
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if((mask & txByte) == 0)
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SDA_SET(bus, LOW);
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else
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SDA_SET(bus, HIGH);
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delay_us(1); // data set-up time (t_SU;DAT)
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SCL_SET(bus, HIGH);
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delay_us(1); // SCL high time (t_HIGH)
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SCL_SET(bus, LOW);
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delay_us(1); // data hold time(t_HD;DAT)
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}
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/* Wait for ACK/NAK */
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SDA_IN(bus);
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SCL_SET(bus, HIGH); // clk #9 for ack
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delay_us(1); // data set-up time (t_SU;DAT)
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/* High level means NAK */
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if( SDA_GET(bus) )
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error = ACK_ERROR;
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SCL_SET(bus, LOW);
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delay_us(1);
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return error;
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}
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static inline uint8_t I2C_WaitWhileClockStreching(uint8_t bus, uint8_t timeout)
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{
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uint8_t error = NO_ERROR;
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while( SCL_GET(bus)== 0)
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{
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if(timeout-- == 0)
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return TIMEOUT_ERROR;
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delay_us(10);
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}
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return error;
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}
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uint8_t I2C_ReadByte(uint8_t bus, uint8_t *rxByte, uint8_t ack, uint32_t timeout)
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{
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//==============================================================================
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uint8_t error = NO_ERROR;
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uint8_t mask;
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*rxByte = 0x00;
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SDA_IN(bus);
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/* start read 8 bits data */
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for(mask = 0x80; mask > 0; mask >>= 1)
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{
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SCL_SET(bus, HIGH); // start clock on SCL-line
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delay_us(1); // clock set-up time (t_SU;CLK)
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// wait while clock streching
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error = I2C_WaitWhileClockStreching(bus, timeout);
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delay_us(1); // SCL high time (t_HIGH)
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if( SDA_GET(bus) )
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*rxByte |= mask; // read bit
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SCL_SET(bus, LOW);
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delay_us(1); // data hold time(t_HD;DAT)
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}
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I2C_Ack(bus, ack);
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return error;
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}
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uint8_t I2C_SendAddress(uint8_t bus, uint8_t dir)
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{
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uint8_t addr;
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uint8_t rv;
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if( I2C_WR == dir )
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{
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addr = W_ADDR(i2c_bus[bus].addr);
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}
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else
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{
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addr = R_ADDR(i2c_bus[bus].addr);
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}
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rv=I2C_WriteByte(bus, addr);
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return rv;
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}
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int i2c_init(uint8_t bus, uint8_t addr)
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{
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if( bus >= I2CBUSMAX )
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{
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return -1;
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}
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#if 0
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/* I2C bus used already */
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if( 0x00 != i2c_bus[bus].addr )
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{
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return -2;
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}
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#endif
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/* Set I2C slave address */
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i2c_bus[bus].addr = addr;
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return 0;
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}
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int i2c_term(uint8_t bus)
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{
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if( bus >= I2CBUSMAX )
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{
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return -1;
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}
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/* Set I2C slave address */
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i2c_bus[bus].addr = 0x0;
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return 0;
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}
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int i2c_read(uint8_t bus, uint8_t *buf, int size)
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{
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int i;
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int rv = NO_ERROR;
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uint8_t byte;
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I2C_StartCondition(bus);
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if( NO_ERROR != (rv=I2C_SendAddress(bus, I2C_RD) ) )
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{
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goto OUT;
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}
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for (i=0; i<size; i++)
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{
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if( !I2C_ReadByte(bus, &byte, ACK, I2C_CLK_STRETCH_TIMEOUT) )
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buf[i] = byte;
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else
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goto OUT;
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}
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OUT:
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I2C_StopCondition(bus);
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return rv;
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}
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int i2c_write(uint8_t bus, uint8_t *data, int bytes)
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{
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int i;
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int rv = NO_ERROR;
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if(!data)
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return PARM_ERROR;
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I2C_StartCondition(bus);
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if( NO_ERROR != (rv=I2C_SendAddress(bus, I2C_WR)) )
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{
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goto OUT;
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}
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for (i=0; i<bytes; i++)
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{
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if( NO_ERROR != (rv=I2C_WriteByte(bus, data[i])) )
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{
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break;
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}
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}
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OUT:
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I2C_StopCondition(bus);
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return rv;
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}
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