softwareI2C/i2c.c

#include "i2c.h"

/*
 * @brief 	初始化 I2C 对应的引脚和定时器
 * @param	void
 *
 * @return 	void
*/
void i2cInit(void){
	GPIO_InitTypeDef GPIO_InitStruct;
	I2C_RCC_CLOCK_CMD;
	
	GPIO_InitStruct.GPIO_Mode	= GPIO_Mode_OUT;
	GPIO_InitStruct.GPIO_OType	= GPIO_OType_OD;
	GPIO_InitStruct.GPIO_PuPd	= GPIO_PuPd_NOPULL;
	GPIO_InitStruct.GPIO_Speed	= GPIO_Speed_50MHz;	
	
	GPIO_InitStruct.GPIO_Pin = I2C_SCL_PIN | I2C_SDA_PIN;
	GPIO_Init(I2C_GROUP,&GPIO_InitStruct);
	
	GPIO_SetBits(I2C_GROUP, I2C_SCL_PIN);
	GPIO_SetBits(I2C_GROUP, I2C_SDA_PIN);
	
	// tim2 init
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

	TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF;
	TIM_TimeBaseStructure.TIM_Prescaler = 83;
	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

	TIM_Cmd(TIM2, ENABLE);
}

/*
 * @brief 	延时函数
 * @param	uint32_t us	延时时长 us
 *
 * @return 	void
*/
void i2cDelay_us(uint32_t us){
	TIM_SetCounter(TIM2, 0);
	// wait counter to target
	while(TIM_GetCounter(TIM2) < us);
}

/*
 * @brief 	软件 i2c 引脚操纵函数
 * @param	uint8_t BitValue 0->低电平/1->高电平
 *
 * @return 	void
*/
void i2cCon_SCL(uint8_t BitValue){
	GPIO_WriteBit(I2C_GROUP, I2C_SCL_PIN, (BitAction)(BitValue));
	i2cDelay_us(i2cSpeedDelay);
}
void i2cCon_SDA(uint8_t BitValue){
	GPIO_WriteBit(I2C_GROUP, I2C_SDA_PIN, (BitAction)(BitValue));
	i2cDelay_us(i2cSpeedDelay);
}

/*
 * @brief 	从 i2c SDA 引脚上读取一个 bit 电平
 * @param	void
 *
 * @return 	uint8_t	总线电平状态
*/
uint8_t i2cReceive_SDA(void){
	uint8_t bitValue = GPIO_ReadInputDataBit(I2C_GROUP, I2C_SDA_PIN);
	i2cDelay_us(i2cSpeedDelay);
	return bitValue;
}

/*
 * @brief 	发送起始&终止信号
 * @param	void
 *
 * @return 	void
*/
void i2cSignal_Start(void){
	i2cCon_SDA(1);
	i2cCon_SCL(1);
	i2cCon_SDA(0);
	i2cCon_SCL(0);
}
void i2cSignal_Stop(void){
	i2cCon_SDA(0);
	i2cCon_SCL(1);
	i2cCon_SDA(1);
}

/*
 * @brief 	发送一个 byte 数据
 * @param	uint8_t byte	需要发送的数据
 *
 * @return 	void
*/
void i2cSend_Byte(uint8_t byte){
	for(int i = 0; i < 8; i++){
		i2cCon_SDA(!!(byte & (0x80 >> i)));
		i2cCon_SCL(1);
		i2cCon_SCL(0);
	}
}

/*
 * @brief 	接收一个 byte 数据
 * @param	void
 *
 * @return 	uint8_t	接收到的数据
*/
uint8_t i2cReceive_Byte(void){
	uint8_t rByte = 0x00;
	i2cCon_SDA(1);
	
	for(int i = 0; i < 8; i++){
		i2cCon_SCL(1);
		
		if(i2cReceive_SDA() == 1){
			rByte |= (0x80 >> i);
		}
		
		i2cCon_SCL(0);
	}
	
	return rByte;
}

/*
 * @brief 	发送应答信号
 * @param	uint8_t ackBit	0->无应答/1->应答
 *
 * @return 	void
*/
void i2cSend_ACK(uint8_t ackBit){
	i2cCon_SDA(ackBit);
	i2cCon_SCL(1);
	i2cCon_SCL(0);
}

/*
 * @brief 	接收应答信号
 * @param	void
 *
 * @return 	uint8_t	是否有应答
*/
uint8_t i2cReceive_ACK(void){
	i2cCon_SDA(1);
	i2cCon_SCL(1);
	uint8_t ackBit = i2cReceive_SDA();
	i2cCon_SCL(0);
	return ackBit;
}