#include "i2c.h"

// 初始化软件 I2C
void i2cInit(void){
	/* 初始化需要操作的 I2C IO */
	GPIO_InitTypeDef GPIO_InitStruct;
	
	// enable gpiob for rcc_ahb1
	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);
	
	// 初始化 I2C 引脚为高电平
	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);
	
	// 初始化完毕后等待 1ms 可酌情删除
	//i2cDelay_us(1000);
}

/* us 级延时 */
void i2cDelay_us(uint32_t us){
	TIM_SetCounter(TIM2, 0);
	// wait counter to target
	while(TIM_GetCounter(TIM2) < us);
}

/* 基本控制函数 */
// 总线电平控制
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);
}

// 读取 SDA 数据
uint8_t i2cReceive_SDA(void){
	uint8_t bitValue = GPIO_ReadInputDataBit(I2C_GROUP, I2C_SDA_PIN);
	i2cDelay_us(i2cSpeedDelay);
	return bitValue;
}

/* 基本时序单元 */
// 开始信号和结束信号
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);
}

/* 数据收发 */
// 发送一个字节
void i2cSend_Byte(uint8_t byte){
	for(int i = 0; i < 8; i++){
		i2cCon_SDA(!!(byte & (0x80 >> i)));
		i2cCon_SCL(1);
		i2cCon_SCL(0);
	}
}
// 接收一个字节
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;
}

/* 应答位操作 */
void i2cSend_ACK(uint8_t ackBit){
	i2cCon_SDA(ackBit);
	i2cCon_SCL(1);
	i2cCon_SCL(0);
}
uint8_t i2cReceive_ACK(void){
	i2cCon_SDA(1);
	i2cCon_SCL(1);
	uint8_t ackBit = i2cReceive_SDA();
	i2cCon_SCL(0);
	return ackBit;
}