rt-thread开发之sccb通讯协议记录(用于ov7670)

头文件

/** Copyright (c) 2024-2024，shchl** SPDX-License-Identifier: Apache-2.0** Change Logs:* Date           Author       Notes* 2024-3-26     shchl   first version*/#ifndef F4_OS_SCCB_H
#define F4_OS_SCCB_H#include "board.h"#define SCCB_ID             0X42     //OV7670的ID#define SCCB_SDA_PIN GET_PIN(D,7)
#define SCCB_SCL_PIN GET_PIN(D,6)
#define SCCB_READ_SDA rt_pin_read(SCCB_SDA_PIN)
///
void sccb_msp_init(void);uint8_t sccb_write_reg(uint8_t reg, uint8_t data);uint8_t sccb_read_reg(uint8_t reg);#endif //F4_OS_SCCB_H

源文件

/** Copyright (c) 2024-2024，shchl** SPDX-License-Identifier: Apache-2.0** Change Logs:* Date           Author       Notes* 2024-3-26     shchl   first version*/#include "sccb.h"
/*------------------------------------根据对应的环境进行修改------------------------------------------------*/
#define SCCB_SCL_H rt_pin_write(SCCB_SCL_PIN, PIN_HIGH)
#define SCCB_SCL_L rt_pin_write(SCCB_SCL_PIN, PIN_LOW)
#define SCCB_SDA_H rt_pin_write(SCCB_SDA_PIN, PIN_HIGH)
#define SCCB_SDA_L rt_pin_write(SCCB_SDA_PIN, PIN_LOW)
#if 1 /*针对sda io 口 需要上拉的 情况*/
#define SCCB_SDA_OUT() rt_pin_mode(SCCB_SDA_PIN, PIN_MODE_OUTPUT)
#define SCCB_SDA_IN() rt_pin_mode(SCCB_SDA_PIN, PIN_MODE_INPUT_PULLUP)
#else
#define SCCB_SDA_OUT()
#define SCCB_SDA_IN() rt_pin_mode(SCCB_SDA_PIN,PIN_MODE_OUTPUT_OD)
#endif/*----------------------------------------------------------------------------------------------------*/
static inline void sccb_delay() {rt_hw_us_delay(50);
}//初始化SCCB接口
//CHECK OK
void sccb_msp_init(void) {SCCB_SDA_IN();rt_pin_mode(SCCB_SCL_PIN, PIN_MODE_OUTPUT);SCCB_SCL_H;SCCB_SDA_OUT();
}//SCCB起始信号
//当时钟为高的时候,数据线的高到低,为SCCB起始信号
//在激活状态下,SDA和SCL均为低电平
static void sccb_start(void) {SCCB_SDA_H;         //数据线高电平SCCB_SCL_H;        //在时钟线高的时候数据线由高至低sccb_delay();SCCB_SDA_L;sccb_delay();SCCB_SCL_L;        //数据线恢复低电平，单操作函数必要
}//SCCB停止信号
//当时钟为高的时候,数据线的低到高,为SCCB停止信号
//空闲状况下,SDA,SCL均为高电平
static void sccb_stop(void) {SCCB_SDA_L;sccb_delay();SCCB_SCL_H;sccb_delay();SCCB_SDA_H;sccb_delay();
}//产生NA信号
static void sccb_no_ack(void) {sccb_delay();SCCB_SDA_H;SCCB_SCL_H;sccb_delay();SCCB_SCL_L;sccb_delay();SCCB_SDA_L;sccb_delay();
}//SCCB,写入一个字节
//返回值:0,成功;1,失败. 
static uint8_t sccb_write_byte(uint8_t dat) {uint8_t j, res;for (j = 0; j < 8; j++) //循环8次发送数据{if (dat & 0x80)SCCB_SDA_H;elseSCCB_SDA_L;dat <<= 1;sccb_delay();SCCB_SCL_H;sccb_delay();SCCB_SCL_L;}SCCB_SDA_IN();        //设置SDA为输入sccb_delay();SCCB_SCL_H;            //接收第九位,以判断是否发送成功sccb_delay();if (SCCB_READ_SDA)res = 1;  //SDA=1发送失败，返回1else res = 0;         //SDA=0发送成功，返回0SCCB_SCL_L;SCCB_SDA_OUT();        //设置SDA为输出return res;
}//SCCB 读取一个字节
//在SCL的上升沿,数据锁存
//返回值:读到的数据
static uint8_t sccb_read_byte(void) {uint8_t temp = 0, j;SCCB_SDA_IN();        //设置SDA为输入for (j = 8; j > 0; j--)    //循环8次接收数据{sccb_delay();SCCB_SCL_H;temp = temp << 1;if (SCCB_READ_SDA)temp++;sccb_delay();SCCB_SCL_L;}SCCB_SDA_OUT();        //设置SDA为输出return temp;
}//写寄存器
//返回值:0,成功;1,失败.
uint8_t sccb_write_reg(uint8_t reg, uint8_t data) {uint8_t res = 0;sccb_start();                    //启动SCCB传输if (sccb_write_byte(SCCB_ID))res = 1;    //写器件IDsccb_delay();if (sccb_write_byte(reg))res = 1;        //写寄存器地址sccb_delay();if (sccb_write_byte(data))res = 1;    //写数据sccb_stop();return res;
}//读寄存器
//返回值:读到的寄存器值
uint8_t sccb_read_reg(uint8_t reg) {uint8_t val = 0;sccb_start();                //启动SCCB传输sccb_write_byte(SCCB_ID);        //写器件IDsccb_delay();sccb_write_byte(reg);            //写寄存器地址sccb_delay();sccb_stop();sccb_delay();//设置寄存器地址后，才是读sccb_start();sccb_write_byte(SCCB_ID | 0X01);    //发送读命令sccb_delay();val = sccb_read_byte();            //读取数据sccb_no_ack();sccb_stop();return val;
}