STM32-17 I²C EEPROM

上篇针对AT24C256B DataSheet当中的地址以及功能说明，这一篇会使用STM32去对EEPROM做写入与读取。

首先先看一下接线的部分(x :不用接)

AT24C256BL476RGVCC5VGndGndSCLPB6SDAPB7A0xA1xA2xWDx

照上方的接法地址会变成(1 0 1 0 0 0 0 R/W )，这时就可以知道写入与读取的设备地址拉，分别是0XA0(写入)与0XA1(读取)。

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程式

I2C Start :

void I2C_Start(){HAL_GPIO_WritePin(GPIOB, SCL_Pin, SET);HAL_GPIO_WritePin(GPIOB, SDA_Pin, SET);HAL_Delay(1);HAL_GPIO_WritePin(GPIOB, SDA_Pin, RESET);HAL_Delay(1);HAL_GPIO_WritePin(GPIOB, SCL_Pin, RESET);HAL_Delay(1);}}

I2C Stop :

void I2C_Stop(){HAL_GPIO_WritePin(GPIOB, SDA_Pin, RESET);HAL_GPIO_WritePin(GPIOB, SCL_Pin, SET);HAL_Delay(1);HAL_GPIO_WritePin(GPIOB, SDA_Pin, SET);}

I2C_Write

void I2C_WriteByte(unsigned char dat){unsigned char i = 0;for(i=0;i<8;i++){//HAL_GPIO_WritePin(GPIOB, SCL_Pin, 0);if(dat & 0x80)HAL_GPIO_WritePin(GPIOB,SDA_Pin ,1);elseHAL_GPIO_WritePin(GPIOB, SDA_Pin, 0);HAL_GPIO_WritePin(GPIOB, SCL_Pin, 1);dat<<=1;HAL_GPIO_WritePin(GPIOB, SCL_Pin, 0);}HAL_GPIO_WritePin(GPIOB, SDA_Pin, 0);HAL_GPIO_WritePin(GPIOB, SCL_Pin, 0);HAL_GPIO_WritePin(GPIOB, SCL_Pin, 1);HAL_GPIO_WritePin(GPIOB, SCL_Pin, 0);}

I2C_Read

unsigned char I2C_ReadByte(int ACK){unsigned char dat = 0, i = 0;for(i = 0; i < 8; i++){HAL_GPIO_WritePin(GPIOB, SCL_Pin, 1);dat<<=1;if(HAL_GPIO_ReadPin(GPIOC, GPIO_PIN_3)==1){dat |= 0x01;}//HAL_GPIO_WritePin(GPIOB, SCL_Pin, 1);HAL_GPIO_WritePin(GPIOB, SCL_Pin, 0);}if(ACK == 1)HAL_GPIO_WritePin(GPIOB, SDA_Pin, 0);elseHAL_GPIO_WritePin(GPIOB, SDA_Pin, 1);HAL_GPIO_WritePin(GPIOB, SCL_Pin, SET);HAL_GPIO_WritePin(GPIOB, SCL_Pin, RESET);HAL_GPIO_WritePin(GPIOB, SDA_Pin, RESET);return dat;}

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AT24C256B 函数

AT24C256_Write

void At24c256_Write(unsigned char Paddr,unsigned char Waddr, unsigned char dat){I2C_Start();I2C_WriteByte(0xA0);HAL_Delay(1);I2C_WriteByte(Paddr);HAL_Delay(1);I2C_WriteByte(Waddr);HAL_Delay(1);I2C_WriteByte(dat);HAL_Delay(1);I2C_Stop();}

AT24C256_Read

unsigned char At24c256_Read(unsigned char Paddr ,unsigned char Addr){unsigned char dat = 0;I2C_Start();I2C_WriteByte(0xA0);HAL_Delay(1);I2C_WriteByte(Paddr);HAL_Delay(1);I2C_WriteByte(Addr);I2C_Start();I2C_WriteByte(0xA1);HAL_Delay(1);dat = I2C_ReadByte(0);HAL_Delay(1);I2C_Stop();return dat;}

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LA分析

手边有LA可以接上去看看I2C是否正确，地址会显示0x50是正常的因为最低位是R/W，实际地址为 1 0 1 0 0 0 0!
可以确定一下在写入每一笔资料时是ACK(也就是SDA = 0)，而读取资料是NACK(也就是SDA = 1)。