119 lines
2.4 KiB
C
119 lines
2.4 KiB
C
#include "i2c.h"
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// 初始化软件 I2C
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void i2cInit(void){
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/* 初始化需要操作的 I2C IO */
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GPIO_InitTypeDef GPIO_InitStruct;
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// enable gpiob for rcc_ahb1
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I2C_RCC_CLOCK_CMD;
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GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
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GPIO_InitStruct.GPIO_OType = GPIO_OType_OD;
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GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
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GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
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GPIO_InitStruct.GPIO_Pin = I2C_SCL_PIN | I2C_SDA_PIN;
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GPIO_Init(I2C_GROUP,&GPIO_InitStruct);
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// 初始化 I2C 引脚为高电平
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GPIO_SetBits(I2C_GROUP, I2C_SCL_PIN);
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GPIO_SetBits(I2C_GROUP, I2C_SDA_PIN);
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// tim2 init
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RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
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TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
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TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF;
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TIM_TimeBaseStructure.TIM_Prescaler = 83;
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TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
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TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
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TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
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TIM_Cmd(TIM2, ENABLE);
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// 初始化完毕后等待 1ms 可酌情删除
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//i2cDelay_us(1000);
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}
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/* us 级延时 */
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void i2cDelay_us(uint32_t us){
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TIM_SetCounter(TIM2, 0);
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// wait counter to target
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while(TIM_GetCounter(TIM2) < us);
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}
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/* 基本控制函数 */
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// 总线电平控制
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void i2cCon_SCL(uint8_t BitValue){
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GPIO_WriteBit(I2C_GROUP, I2C_SCL_PIN, (BitAction)(BitValue));
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i2cDelay_us(i2cSpeedDelay);
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}
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void i2cCon_SDA(uint8_t BitValue){
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GPIO_WriteBit(I2C_GROUP, I2C_SDA_PIN, (BitAction)(BitValue));
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i2cDelay_us(i2cSpeedDelay);
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}
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// 读取 SDA 数据
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uint8_t i2cReceive_SDA(void){
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uint8_t bitValue = GPIO_ReadInputDataBit(I2C_GROUP, I2C_SDA_PIN);
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i2cDelay_us(i2cSpeedDelay);
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return bitValue;
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}
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/* 基本时序单元 */
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// 开始信号和结束信号
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void i2cSignal_Start(void){
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i2cCon_SDA(1);
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i2cCon_SCL(1);
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i2cCon_SDA(0);
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i2cCon_SCL(0);
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}
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void i2cSignal_Stop(void){
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i2cCon_SDA(0);
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i2cCon_SCL(1);
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i2cCon_SDA(1);
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}
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/* 数据收发 */
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// 发送一个字节
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void i2cSend_Byte(uint8_t byte){
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for(int i = 0; i < 8; i++){
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i2cCon_SDA(!!(byte & (0x80 >> i)));
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i2cCon_SCL(1);
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i2cCon_SCL(0);
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}
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}
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// 接收一个字节
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uint8_t i2cReceive_Byte(void){
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uint8_t rByte = 0x00;
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i2cCon_SDA(1);
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for(int i = 0; i < 8; i++){
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i2cCon_SCL(1);
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if(i2cReceive_SDA() == 1){
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rByte |= (0x80 >> i);
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}
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i2cCon_SCL(0);
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}
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return rByte;
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}
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/* 应答位操作 */
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void i2cSend_ACK(uint8_t ackBit){
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i2cCon_SDA(ackBit);
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i2cCon_SCL(1);
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i2cCon_SCL(0);
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}
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uint8_t i2cReceive_ACK(void){
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i2cCon_SDA(1);
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i2cCon_SCL(1);
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uint8_t ackBit = i2cReceive_SDA();
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i2cCon_SCL(0);
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return ackBit;
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}
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