软件模拟IIC的全面笔记(已调通)
@[toc] lib_i2c_simulation
/*
* @Author: Haiyichen
* @Date: 2023-09-21 16:16:16
* @LastEditors: Haiyichen
* @LastEditTime: 2023-10-31 18:01:10
* @Description: Personal notes of i2c-simulation
*/
i2c基础
通讯流程
协议
除了文字解释，有用wavedrom简单画了一些各种信号的电平变化过程，但需要支持MPE才能看到，虽然CSDN上的在线编辑器无法渲染出图，但还是放出来了，如果有条件可以在自己的VSCode中配置MPE(markdown preview enhenced)
- 开始：SCL为高电平时，SDA从高电平状态切换到低电平状态。
{signal:[ { name:'SCL', wave:'p.Pp'}, { name:'data', wave:"x.=x", data:["Start" ]}, { name:'SDA', wave:"1.0"} ]} - 停止：SCL为高电平时，SDA从低电平状态切换到高电平状态。
{signal:[ { name:'SCL', wave:'p.PPp'}, { name:'data', wave:"x.=x", data:["Stop" ]}, { name:'SDA', wave:"0.10"} ]} - 应答:发送侧发送完8bit数据后，接收侧需要回复一个信号，即第9个SCL时，接收侧将SDA拉低，称作ACK。
{signal:[ { name:'SCL', wave:'p.Pp..|Pp'}, { name:'data', wave:"x.==..|=x", data:["Start", "SlaveAddress","Ack"]}, { name:'SDA', wave:"0.10.1|0."} ]} - 无应答：发送侧发送完8bit数据后，接收侧需要回复一个信号，即第9个SCL时，接收侧将SDA拉高（或叫释放SDA），称作NACK。NACK时同时会引起Master发生RESTART或STOP流程。
{signal:[ { name:'SCL', wave:'p.Pp..|Pp'}, { name:'data', wave:"x.==..|=x", data:["Start", "SlaveAddress","Nack"]}, { name:'SDA', wave:"0.10.0|1."} ]} - 地址命令:i2c的地址是7bit，第8bit是方向位。1代表Read、0代表Write
写流程
- Master发起START
- Master发送Slave地址(7bit)和W(0:写动作)，等待Slave发动应答ACK
- Slave发送应答ACK
- Master发送寄存器地址(8bit),等待Slave发送应答ACK
- Slave发送应答ACK
- Master发送写入寄存器的数据(8bit),等待Slave发送应答ACK
- Slave发送应答ACK
- 6~7可以循环多次，即按顺序写多个寄存器
- Master发起STOP
读流程
- Master发起START
- Master发送Slave地址(7bit)和W(0:写动作),等待Slave发送应答ACK
- Slave发送应答ACK
- Master发送寄存器地址(8bit),等待Slave发送应答ACK
- Slave发送应答ACK
- Master发起START
- Master发送Slave地址(7bit)和R(1:读动作),等待Slave发送应答ACK
- Slave发送应答ACK
- Slave发送寄存器里数据(8bit),等待Master发送ACK
- Master发送ACK或NACK(出现NACK，后面直接就是STOP流程)
- 9~10可以循环多次，即顺序读多个寄存器
- Master发起STOP
i2c模拟驱动函数
相关硬件配置
/* IO definition of i2c simulation */
#define I2C_SIMULATION_GPIO_PORT GPIOA
#define I2C_SIMULATION_SCL_PIN GPIO_PINS_0
#define I2C_SIMULATION_SDA_PIN GPIO_PINS_1
/* driver definition of i2c simulation for M1 */
#define I2C_SDA_H() I2C_SIMULATION_GPIO_PORT->scr = I2C_SIMULATION_SDA_PIN;
#define I2C_SDA_L() I2C_SIMULATION_GPIO_PORT->clr = I2C_SIMULATION_SDA_PIN;
#define I2C_SCL_H() I2C_SIMULATION_GPIO_PORT->scr = I2C_SIMULATION_SCL_PIN;
#define I2C_SCL_L() I2C_SIMULATION_GPIO_PORT->clr = I2C_SIMULATION_SCL_PIN;
关于模拟i2c的IO配置细节
关于SDA引脚是配置成开漏还是推挽,
- 推挽输出对应->需要切换输入输出模式；
- 开漏输出对应->不需要切换输入输出模式.
参考链接已验证
i2c_Delay()
//需要根据主控MCU频率和i的取值，调整i2c_Delay的时长，进而调整SCL的脉宽。(也受编译器“优化等级”影响)
/**
* @name i2c_Delay
* @brief soft delay for i2c clock
* @param none
* @retval none
*/
static void i2c_Delay(void)
{
uint8_t i;
/*
*AT32F425F6P7,
*i = 100,SCL = 163.4KHZ,6.1us
*i = 75, SCL = 243.9KHZ,4.1us
*i = 50, SCL = 312.5kHZ,3.2us
*/
for(i=0;i<100;i++);
}
hw_i2c_START()
/**
* @name hw_i2c_START
* @brief start signal for i2c simulation
* @param none
* @retval none
*/
void hw_i2c_START(void)
{
I2C_SDA_H();
I2C_SCL_H();
i2c_Delay();
I2C_SDA_L();
i2c_Delay();
I2C_SCL_L();
i2c_Delay();
}
hw_i2c_ACK()
/**
* @name hw_i2c_ACK
* @brief ACK signal for i2c simulation
* @param none
* @retval none
*/
void hw_i2c_ACK(void)
{
I2C_SDA_L();
i2c_Delay();
I2C_SCL_H();
i2c_Delay();
I2C_SCL_L();
i2c_Delay();
I2C_SDA_H();
}
hw_i2c_WaitAck()
/**
* @name hw_i2c_WaitAck
* @brief Wait ACK signal for i2c simulation
* @param none
* @retval uint8_t tempRe：Get slave ack signal or not
*/
uint8_t hw_i2c_WaitAck(void)
{
uint8_t tempRe;
I2C_SDA_H(); //MCU(master) set SDA High
i2c_Delay();
I2C_SCL_H(); //MCU(master) send a new SCL signal, slave device should return an Ack signal
i2c_Delay();
tempRe = I2C_SDA_READ(); //MCU(master) read SDA state(1 or 0)
I2C_SCL_L();
i2c_Delay();
return tempRe;
}
hw_i2c_NACK()
/**
* @name hw_i2c_NACK
* @brief Send NACK signal to slave for i2c simulation
* @param none
* @retval none
*/
void hw_i2c_NACK(void)
{
I2C_SDA_L();
I2C_SCL_H();
i2c_Delay();
I2C_SDA_H();
}
hw_i2c_STOP()
/**
* @name hw_i2c_STOP
* @brief Send STOP signal to slave for i2c simulation
* @param none
* @retval none
*/
void hw_i2c_STOP(void)
{
I2C_SDA_L();
I2C_SCL_H();
i2c_Delay();
I2C_SDA_H();
i2c_Delay();
}
lib_i2c_SendByte()
/**
* @name lib_i2c_SendByte
* @brief Send Byte from master by simulation of i2c
* @param DataByte:data
* @retval none
*/
void lib_i2c_SendByte(uint8_t DataByte)
{
uint8_t i;
for ( i = 0; i < 8; i++)
{
if (DataByte & 0x80)
{
I2C_SDA_H();
}
else
{
I2C_SDA_L();
}
i2c_Delay();
I2C_SCL_H();
i2c_Delay();
I2C_SCL_L();
if (i == 7)
{
I2C_SDA_H(); //MCU(master) set SDA high
}
DataByte <<= 1;
i2c_Delay();
}
}
lib_i2c_ReadByte()
/**
* @name lib_i2c_ReadByte
* @brief Read Byte from slave device by simulation of i2c
* @param none
* @retval tempData:data
*/
uint8_t lib_i2c_ReadByte(void)
{
uint8_t i;
uint8_t tempData = 0;
uint8_t tempRe = 0;
for(i = 0; i < 8; i++)
{
tempData <<=1;
I2C_SCL_H();
i2c_Delay();
tempRe = I2C_SDA_READ();
if(tempRe)
{
tempData++;
}
I2C_SCL_L();
i2c_Delay();
}
return tempData;
}
lib_i2c_ReadMutiBytes()
/**
* @name lib_i2c_ReadMutiBytes
* @brief Read Muti Bytes data from slave device
* @param slave_address
* @param reg_address
* @param pdatabuf
* @param len
* @retval tempRe:whether read data successfully or not
*/
uint8_t lib_i2c_ReadMutiBytes(uint8_t slave_address, uint8_t reg_address, uint8_t* pdatabuf, uint8_t len)
{
uint8_t tempData;
uint8_t tempRe = 0;
uint8_t cnt = 0;
uint8_t tempaddr_W = slave_address<<1;
uint8_t tempaddr_R = tempaddr_W + 1;
do
{
/* 1st:i2c start signal */
hw_i2c_START();
/* 2nd:write slave device address, bit0 is a read-write control bit, 0 for write, and 1 for read */
lib_i2c_SendByte(tempaddr_W);
/* 3rd:wait ack from slave device */
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
/* 4th:send target register address */
lib_i2c_SendByte(reg_address);
/* 5th:wait Ack from slave device */s
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
/* 6th:send a start signal to reset i2c bus, and then start to read data from slave device */
hw_i2c_START();
/* 7th:Send a read command(bit0) for the slave address */
lib_i2c_SendByte(tempaddr_R);
/* 8th:wait Ack from slave device */
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
//9th:read data by loop
for(cnt = 0; cnt < len; cnt++)
{
pdatabuf[cnt] = lib_i2c_ReadByte(); //read 1 byte
/* After reading each byte, an Ack needs to be sent, except for the last byte, which requires a Nack */
if(cnt != len - 1)
{
/* After the middle byte is read, the CPU generates the ACK signal (Drive SDA = 0) */
hw_i2c_ACK();
}
else
{
/* After reading the last byte, the CPU generates the NACK signal (drive SDA = 1) */
hw_i2c_NACK();
}
}
}while(0);
/* Send I2C bus stop signal */
hw_i2c_STOP();
if(tempRe){
tempRe = 0;
}else{
tempRe = 1;
}
return tempRe;
}
lib_i2c_WriteSingleByte()
/**
* @brief write single byte through the i2c1(For M1) by sofyware simulation.
* @param slave_address: address of tagert slave device
* @param reg_address: address of tagert register
* @param pdata: pointer to the data
* @retval tempRe: Write data successfully or not
*/
uint8_t lib_i2c_WriteSingleByte(uint16_t slave_address, uint16_t reg_address, uint8_t pdata)
{
uint8_t tempRe = 0;
uint8_t tempData = pdata;
uint16_t tempaddr = slave_address<<1;
do
{
hw_i2c_START();
lib_i2c_SendByte(tempaddr);
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
lib_i2c_SendByte(reg_address);
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
lib_i2c_SendByte(tempData);
tempRe = hw_i2c_WaitAck();
if (tempRe){ // the return value is 1 ,that is to say SDA is not lowwed. the target ist8310 doesn't Ack
break;
}
hw_i2c_STOP();
} while (0);
return tempRe;
}
小结
因为用的芯片硬件IIC的底层官方函数一直卡死跑不通，于是干脆自己整理了一套软件模拟IIC的相关流程和函数，已经在项目中顺利调通了，项目换芯片也经历过不同芯片的移植，也很方便。