/**********************************************************************
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* Copyright: (C)2024 LingYun IoT System Studio
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* Author: GuoWenxue<guowenxue@gmail.com>
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*
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* Description: The purpose of this code is to provide a simple C library,
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* which providing software bit-bang of the I2C protocol on
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* any GPIO pins for ISKBoard.
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*
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* ChangeLog:
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* Version Date Author Description
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* V1.0.0 2024.08.29 GuoWenxue Release initial version
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*
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***********************************************************************/
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#include "i2c_bitbang.h"
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#include "miscdev.h" /* udelay() implement by TIM6 */
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/*
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*+---------------------------------+
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*| I2C GPIO port Level functions |
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*+---------------------------------+
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*/
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#define mdelay(ms) HAL_Delay(ms)
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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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i2c_bus_t i2c_bus =
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{
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/* Addr SCL_Pin SDA_Pin */
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0x00, {GPIOB, GPIO_PIN_6 }, {GPIOB, GPIO_PIN_7 }, /* SHT20, RTC, OLED */
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};
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static inline void SDA_IN(void)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_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.sda.group, &GPIO_InitStruct);
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}
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static inline void SDA_OUT(void)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_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.sda.group, &GPIO_InitStruct);
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}
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static inline void SCL_OUT(void)
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{
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GPIO_InitTypeDef GPIO_InitStruct = {0};
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GPIO_InitStruct.Pin = i2c_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.scl.group, &GPIO_InitStruct);
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}
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static inline void SCL_SET(int level)
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{
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HAL_GPIO_WritePin(i2c_bus.scl.group, i2c_bus.scl.pin, level?GPIO_PIN_SET:GPIO_PIN_RESET);
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}
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static inline void SDA_SET(int level)
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{
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HAL_GPIO_WritePin(i2c_bus.sda.group, i2c_bus.sda.pin, level?GPIO_PIN_SET:GPIO_PIN_RESET);
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}
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static inline GPIO_PinState SCL_GET(void)
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{
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return HAL_GPIO_ReadPin(i2c_bus.scl.group, i2c_bus.scl.pin);
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}
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static inline GPIO_PinState SDA_GET(void)
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{
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return HAL_GPIO_ReadPin(i2c_bus.sda.group, i2c_bus.sda.pin);
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}
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/*
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*+--------------------------------+
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*| I2C Low Level API functions |
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*+--------------------------------+
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*/
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void I2C_StartCondition(void)
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{
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SDA_OUT();
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SCL_OUT();
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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(HIGH);
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SCL_SET( HIGH);
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udelay(1);
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SDA_SET(LOW);
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udelay(1); // hold time start condition (t_HD;STA)
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SCL_SET(LOW);
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udelay(1);
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}
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void I2C_StopCondition(void)
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{
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SDA_OUT();
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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(LOW);
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SDA_SET(LOW);
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udelay(1);
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SCL_SET(HIGH);
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SDA_SET(HIGH);
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udelay(1);
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}
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int I2C_SendAddress(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.addr);
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}
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else
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{
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addr = R_ADDR(i2c_bus.addr);
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}
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rv=I2C_WriteByte(addr);
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return rv;
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}
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void I2C_Ack(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(LOW);
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SDA_OUT();
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if( ACK==ack )
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SDA_SET(LOW);
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else if( NAK==ack )
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SDA_SET(HIGH);
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udelay(1);
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SCL_SET( HIGH);
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udelay(1);
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SCL_SET(LOW);
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}
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int I2C_WriteByte(uint8_t txByte)
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{
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int error = 0;
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uint8_t mask;
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SDA_OUT();
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SCL_SET(LOW);
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/* start send 8 bits data, MSB */
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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(LOW);
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else
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SDA_SET(HIGH);
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udelay(1); // data set-up time (t_SU;DAT)
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SCL_SET(HIGH);
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udelay(1); // SCL high time (t_HIGH)
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SCL_SET(LOW);
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udelay(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();
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SCL_SET(HIGH); // clk #9 for ack
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udelay(1); // data set-up time (t_SU;DAT)
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/* High level means NAK */
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if( SDA_GET() )
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error = -ERROR_ACK;
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SCL_SET(LOW);
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udelay(1);
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return error;
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}
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static inline int I2C_WaitWhileClockStreching(uint8_t timeout)
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{
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while( SCL_GET()== 0)
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{
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if(timeout-- == 0)
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return -ERROR_TIMEOUT;
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udelay(10);
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}
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return ERROR_NONE;
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}
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int I2C_ReadByte(uint8_t *rxByte, uint8_t ack, uint32_t timeout)
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{
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uint8_t error = 0;
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uint8_t mask;
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*rxByte = 0x00;
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SDA_IN();
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/* start read 8 bits data, MSB */
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for(mask = 0x80; mask > 0; mask >>= 1)
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{
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SCL_SET(HIGH); // start clock on SCL-line
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udelay(1); // clock set-up time (t_SU;CLK)
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// wait while clock streching
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error = I2C_WaitWhileClockStreching(timeout);
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udelay(1); // SCL high time (t_HIGH)
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if( SDA_GET() )
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*rxByte |= mask; // read bit
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SCL_SET(LOW);
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udelay(1); // data hold time(t_HD;DAT)
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}
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I2C_Ack(ack);
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return error;
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}
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/*
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*+--------------------------------+
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*| I2C High Level API functions |
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*+--------------------------------+
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*/
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int i2c_lock(uint8_t addr)
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{
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/* I2C bus already be used */
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while( i2c_bus.addr && i2c_bus.addr!=addr )
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{
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mdelay(10);
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}
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i2c_bus.addr = addr;
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return 0;
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}
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void i2c_free(void)
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{
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i2c_bus.addr = 0x0;
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}
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int i2c_write(uint8_t *data, int bytes)
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{
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int i;
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int rv = 0;
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if( !data )
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{
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return -ERROR_PARM;
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}
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/* send start condition */
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I2C_StartCondition();
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/* send device address for write */
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if( (rv=I2C_SendAddress(I2C_WR)) < 0 )
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goto OUT;
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/* send data to slave device */
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for (i=0; i<bytes; i++)
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{
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if( (rv=I2C_WriteByte(data[i])) < 0 )
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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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/* send stop condition */
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I2C_StopCondition();
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return rv;
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}
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int i2c_read(uint8_t *buf, int size)
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{
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int i;
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int rv = ERROR_NONE;
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uint8_t byte;
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/* send start condition */
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I2C_StartCondition();
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/* send device address for read */
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if( (rv=I2C_SendAddress(I2C_RD)) < 0 )
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goto OUT;
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/* read data from slave device */
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for (i=0; i<size; i++)
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{
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if( (rv=I2C_ReadByte(&byte, ACK, I2C_CLK_STRETCH_TIMEOUT)) < 0 )
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goto OUT;
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buf[i] = byte;
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}
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OUT:
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/* send stop condition */
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I2C_StopCondition();
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return rv;
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}
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