假设硬件电路如下图
EEPROM芯片的设备地址一共有 7 位，其中高 4 位固定为：1010 b，低 3 位则由 A0/A1/A2 信号线的
电平决定，图中的 R/W是读写方向位，与地址无关。
按照我们此处的连接，A0/A1/A2均为0，所以EEPROM的7位设备地址是：101 0000b ，
即 0x50。由于 I2C 通讯时常常是地址跟读写方向连在一起构成一个 8 位数，且当 R/W 位为
0 时，表示写方向，所以加上 7 位地址，其值为“0xA0”，常称该值为 I2C 设备的“写地
址”；当 R/W 位为 1 时，表示读方向，加上 7 位地址，其值为“0xA1”，常称该值为“读地址”。
EEPROM 芯片中还有一个 WP 引脚，具有写保护功能，当该引脚电平为高时，禁止写
入数据，当引脚为低电平时，可写入数据，我们直接接地，不使用写保护功能。
关于 EEPROM 的更多信息，可参考其数据手册《AT24C02》来了解。若您使用的实验
板 EEPROM 的型号、设备地址或控制引脚不一样，只需根据我们的工程修改即可，程序的
控制原理相同。
编程要点
(1) 配置通讯使用的目标引脚为开漏模式；
(2) 使能 I2C外设的时钟；
(3) 配置 I2C外设的模式、地址、速率等参数并使能 I2C外设；
(4) 编写基本 I2C按字节收发的函数；
(5) 编写读写 EEPROM 存储内容的函数；
(6) 编写测试程序，对读写数据进行校验。
#include "stm32f10x.h"
/**************************I2C参数定义，I2C1或I2C2********************************/
#define EEPROM_I2Cx I2C1
#define EEPROM_I2C_APBxClock_FUN RCC_APB1PeriphClockCmd
#define EEPROM_I2C_CLK RCC_APB1Periph_I2C1
#define EEPROM_I2C_GPIO_APBxClock_FUN RCC_APB2PeriphClockCmd
#define EEPROM_I2C_GPIO_CLK RCC_APB2Periph_GPIOB
#define EEPROM_I2C_SCL_PORT GPIOB
#define EEPROM_I2C_SCL_PIN GPIO_Pin_6
#define EEPROM_I2C_SDA_PORT GPIOB
#define EEPROM_I2C_SDA_PIN GPIO_Pin_7
/* STM32 I2C 快速模式 */
#define I2C_Speed 400000 //*
/* 这个地址只要与STM32外挂的I2C器件地址不一样即可 */
#define I2Cx_OWN_ADDRESS7 0X0A
/* AT24C01/02每页有8个字节 */
#define I2C_PageSize 8
/* AT24C04/08A/16A每页有16个字节 */
//#define I2C_PageSize 16
/*等待超时时间*/
#define I2CT_FLAG_TIMEOUT ((uint32_t)0x1000)
#define I2CT_LONG_TIMEOUT ((uint32_t)(10 * I2CT_FLAG_TIMEOUT))
/*信息输出*/
#define EEPROM_DEBUG_ON 0
#define EEPROM_INFO(fmt,arg...) printf("<<-EEPROM-INFO->> "fmt"\n",##arg)
#define EEPROM_ERROR(fmt,arg...) printf("<<-EEPROM-ERROR->> "fmt"\n",##arg)
#define EEPROM_DEBUG(fmt,arg...) do{\
if(EEPROM_DEBUG_ON)\
printf("<<-EEPROM-DEBUG->> [%d]"fmt"\n",__LINE__, ##arg);\
}while(0)
/*
* AT24C02 2kb = 2048bit = 2048/8 B = 256 B
* 32 pages of 8 bytes each
*
* Device Address
* 1 0 1 0 A2 A1 A0 R/W
* 1 0 1 0 0 0 0 0 = 0XA0
* 1 0 1 0 0 0 0 1 = 0XA1
*/
/* EEPROM Addresses defines */
#define EEPROM_Block0_ADDRESS 0xA0 /* E2 = 0 */
//#define EEPROM_Block1_ADDRESS 0xA2 /* E2 = 0 */
//#define EEPROM_Block2_ADDRESS 0xA4 /* E2 = 0 */
//#define EEPROM_Block3_ADDRESS 0xA6 /* E2 = 0 */
void I2C_EE_Init(void);
void I2C_EE_BufferWrite(u8* pBuffer, u8 WriteAddr, u16 NumByteToWrite);
uint32_t I2C_EE_ByteWrite(u8* pBuffer, u8 WriteAddr);
uint32_t I2C_EE_PageWrite(u8* pBuffer, u8 WriteAddr, u8 NumByteToWrite);
uint32_t I2C_EE_BufferRead(u8* pBuffer, u8 ReadAddr, u16 NumByteToRead);
void I2C_EE_WaitEepromStandbyState(void);
/**
******************************************************************************
* @file bsp_i2c_ee.c
* @author STMicroelectronics
* @version V1.0
* @date 2013-xx-xx
* @brief i2c EEPROM(AT24C02)应用函数bsp
******************************************************************************
* @attention
*
* 实验平台:秉火 F103-指南者 STM32 开发板
* 论坛 :http://www.firebbs.cn
* 淘宝 :https://fire-stm32.taobao.com
*
******************************************************************************
*/
#include "./i2c/bsp_i2c_ee.h"
#include "./usart/bsp_usart.h"
uint16_t EEPROM_ADDRESS;
static __IO uint32_t I2CTimeout = I2CT_LONG_TIMEOUT;
static uint32_t I2C_TIMEOUT_UserCallback(uint8_t errorCode);
/**
* @brief I2C I/O配置
* @param 无
* @retval 无
*/
static void I2C_GPIO_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* 使能与 I2C 有关的时钟 */
EEPROM_I2C_APBxClock_FUN ( EEPROM_I2C_CLK, ENABLE );
EEPROM_I2C_GPIO_APBxClock_FUN ( EEPROM_I2C_GPIO_CLK, ENABLE );
/* I2C_SCL、I2C_SDA*/
GPIO_InitStructure.GPIO_Pin = EEPROM_I2C_SCL_PIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD; // 开漏输出
GPIO_Init(EEPROM_I2C_SCL_PORT, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = EEPROM_I2C_SDA_PIN;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD; // 开漏输出
GPIO_Init(EEPROM_I2C_SDA_PORT, &GPIO_InitStructure);
}
/**
* @brief I2C 工作模式配置
* @param 无
* @retval 无
*/
static void I2C_Mode_Configu(void)
{
I2C_InitTypeDef I2C_InitStructure;
/* I2C 配置 */
I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
/* 高电平数据稳定，低电平数据变化 SCL 时钟线的占空比 */
I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
I2C_InitStructure.I2C_OwnAddress1 =I2Cx_OWN_ADDRESS7;
I2C_InitStructure.I2C_Ack = I2C_Ack_Enable ;
/* I2C的寻址模式 */
I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
/* 通信速率 */
I2C_InitStructure.I2C_ClockSpeed = I2C_Speed;
/* I2C 初始化 */
I2C_Init(EEPROM_I2Cx, &I2C_InitStructure);
/* 使能 I2C */
I2C_Cmd(EEPROM_I2Cx, ENABLE);
}
/**
* @brief I2C 外设(EEPROM)初始化
* @param 无
* @retval 无
*/
void I2C_EE_Init(void)
{
I2C_GPIO_Config();
I2C_Mode_Configu();
/* 根据头文件i2c_ee.h中的定义来选择EEPROM的设备地址 */
#ifdef EEPROM_Block0_ADDRESS
/* 选择 EEPROM Block0 来写入 */
EEPROM_ADDRESS = EEPROM_Block0_ADDRESS;
#endif
#ifdef EEPROM_Block1_ADDRESS
/* 选择 EEPROM Block1 来写入 */
EEPROM_ADDRESS = EEPROM_Block1_ADDRESS;
#endif
#ifdef EEPROM_Block2_ADDRESS
/* 选择 EEPROM Block2 来写入 */
EEPROM_ADDRESS = EEPROM_Block2_ADDRESS;
#endif
#ifdef EEPROM_Block3_ADDRESS
/* 选择 EEPROM Block3 来写入 */
EEPROM_ADDRESS = EEPROM_Block3_ADDRESS;
#endif
}
/**
* @brief 将缓冲区中的数据写到I2C EEPROM中
* @param
* @arg pBuffer:缓冲区指针
* @arg WriteAddr:写地址
* @arg NumByteToWrite:写的字节数
* @retval 无
*/
void I2C_EE_BufferWrite(u8* pBuffer, u8 WriteAddr, u16 NumByteToWrite)
{
u8 NumOfPage = 0, NumOfSingle = 0, Addr = 0, count = 0;
Addr = WriteAddr % I2C_PageSize;
count = I2C_PageSize - Addr;
NumOfPage = NumByteToWrite / I2C_PageSize;
NumOfSingle = NumByteToWrite % I2C_PageSize;
/* If WriteAddr is I2C_PageSize aligned */
if(Addr == 0)
{
/* If NumByteToWrite < I2C_PageSize */
if(NumOfPage == 0)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
I2C_EE_WaitEepromStandbyState();
}
/* If NumByteToWrite > I2C_PageSize */
else
{
while(NumOfPage--)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, I2C_PageSize);
I2C_EE_WaitEepromStandbyState();
WriteAddr += I2C_PageSize;
pBuffer += I2C_PageSize;
}
if(NumOfSingle!=0)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
I2C_EE_WaitEepromStandbyState();
}
}
}
/* If WriteAddr is not I2C_PageSize aligned */
else
{
/* If NumByteToWrite < I2C_PageSize */
if(NumOfPage== 0)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
I2C_EE_WaitEepromStandbyState();
}
/* If NumByteToWrite > I2C_PageSize */
else
{
NumByteToWrite -= count;
NumOfPage = NumByteToWrite / I2C_PageSize;
NumOfSingle = NumByteToWrite % I2C_PageSize;
if(count != 0)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, count);
I2C_EE_WaitEepromStandbyState();
WriteAddr += count;
pBuffer += count;
}
while(NumOfPage--)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, I2C_PageSize);
I2C_EE_WaitEepromStandbyState();
WriteAddr += I2C_PageSize;
pBuffer += I2C_PageSize;
}
if(NumOfSingle != 0)
{
I2C_EE_PageWrite(pBuffer, WriteAddr, NumOfSingle);
I2C_EE_WaitEepromStandbyState();
}
}
}
}
/**
* @brief 写一个字节到I2C EEPROM中
* @param
* @arg pBuffer:缓冲区指针
* @arg WriteAddr:写地址
* @retval 无
*/
uint32_t I2C_EE_ByteWrite(u8* pBuffer, u8 WriteAddr)
{
/* Send STRAT condition */
I2C_GenerateSTART(EEPROM_I2Cx, ENABLE);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV5 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_MODE_SELECT))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(0);
}
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Send EEPROM address for write */
I2C_Send7bitAddress(EEPROM_I2Cx, EEPROM_ADDRESS, I2C_Direction_Transmitter);
/* Test on EV6 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(1);
}
/* Send the EEPROM's internal address to write to */
I2C_SendData(EEPROM_I2Cx, WriteAddr);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV8 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(2);
}
/* Send the byte to be written */
I2C_SendData(EEPROM_I2Cx, *pBuffer);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV8 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(3);
}
/* Send STOP condition */
I2C_GenerateSTOP(EEPROM_I2Cx, ENABLE);
return 1;
}
/**
* @brief 在EEPROM的一个写循环中可以写多个字节，但一次写入的字节数
* 不能超过EEPROM页的大小，AT24C02每页有8个字节
* @param
* @arg pBuffer:缓冲区指针
* @arg WriteAddr:写地址
* @arg NumByteToWrite:写的字节数
* @retval 无
*/
uint32_t I2C_EE_PageWrite(u8* pBuffer, u8 WriteAddr, u8 NumByteToWrite)
{
I2CTimeout = I2CT_LONG_TIMEOUT;
while(I2C_GetFlagStatus(EEPROM_I2Cx, I2C_FLAG_BUSY))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(4);
}
/* Send START condition */
I2C_GenerateSTART(EEPROM_I2Cx, ENABLE);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV5 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_MODE_SELECT))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(5);
}
/* Send EEPROM address for write */
I2C_Send7bitAddress(EEPROM_I2Cx, EEPROM_ADDRESS, I2C_Direction_Transmitter);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV6 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(6);
}
/* Send the EEPROM's internal address to write to */
I2C_SendData(EEPROM_I2Cx, WriteAddr);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV8 and clear it */
while(! I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(7);
}
/* While there is data to be written */
while(NumByteToWrite--)
{
/* Send the current byte */
I2C_SendData(EEPROM_I2Cx, *pBuffer);
/* Point to the next byte to be written */
pBuffer++;
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV8 and clear it */
while (!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(8);
}
}
/* Send STOP condition */
I2C_GenerateSTOP(EEPROM_I2Cx, ENABLE);
return 1;
}
/**
* @brief 从EEPROM里面读取一块数据
* @param
* @arg pBuffer:存放从EEPROM读取的数据的缓冲区指针
* @arg WriteAddr:接收数据的EEPROM的地址
* @arg NumByteToWrite:要从EEPROM读取的字节数
* @retval 无
*/
uint32_t I2C_EE_BufferRead(u8* pBuffer, u8 ReadAddr, u16 NumByteToRead)
{
I2CTimeout = I2CT_LONG_TIMEOUT;
//*((u8 *)0x4001080c) |=0x80;
while(I2C_GetFlagStatus(EEPROM_I2Cx, I2C_FLAG_BUSY))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(9);
}
/* Send START condition */
I2C_GenerateSTART(EEPROM_I2Cx, ENABLE);
//*((u8 *)0x4001080c) &=~0x80;
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV5 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_MODE_SELECT))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(10);
}
/* Send EEPROM address for write */
I2C_Send7bitAddress(EEPROM_I2Cx, EEPROM_ADDRESS, I2C_Direction_Transmitter);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV6 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(11);
}
/* Clear EV6 by setting again the PE bit */
I2C_Cmd(EEPROM_I2Cx, ENABLE);
/* Send the EEPROM's internal address to write to */
I2C_SendData(EEPROM_I2Cx, ReadAddr);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV8 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(12);
}
/* Send STRAT condition a second time */
I2C_GenerateSTART(EEPROM_I2Cx, ENABLE);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV5 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_MODE_SELECT))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(13);
}
/* Send EEPROM address for read */
I2C_Send7bitAddress(EEPROM_I2Cx, EEPROM_ADDRESS, I2C_Direction_Receiver);
I2CTimeout = I2CT_FLAG_TIMEOUT;
/* Test on EV6 and clear it */
while(!I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED))
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(14);
}
/* While there is data to be read */
while(NumByteToRead)
{
if(NumByteToRead == 1)
{
/* Disable Acknowledgement */
I2C_AcknowledgeConfig(EEPROM_I2Cx, DISABLE);
/* Send STOP Condition */
I2C_GenerateSTOP(EEPROM_I2Cx, ENABLE);
}
/* Test on EV7 and clear it */
I2CTimeout = I2CT_LONG_TIMEOUT;
while(I2C_CheckEvent(EEPROM_I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED)==0)
{
if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback(3);
}
{
/* Read a byte from the EEPROM */
*pBuffer = I2C_ReceiveData(EEPROM_I2Cx);
/* Point to the next location where the byte read will be saved */
pBuffer++;
/* Decrement the read bytes counter */
NumByteToRead--;
}
}
/* Enable Acknowledgement to be ready for another reception */
I2C_AcknowledgeConfig(EEPROM_I2Cx, ENABLE);
return 1;
}
/**
* @brief Wait for EEPROM Standby state
* @param 无
* @retval 无
*/
void I2C_EE_WaitEepromStandbyState(void)
{
vu16 SR1_Tmp = 0;
do
{
/* Send START condition */
I2C_GenerateSTART(EEPROM_I2Cx, ENABLE);
/* Read I2C1 SR1 register */
SR1_Tmp = I2C_ReadRegister(EEPROM_I2Cx, I2C_Register_SR1);
/* Send EEPROM address for write */
I2C_Send7bitAddress(EEPROM_I2Cx, EEPROM_ADDRESS, I2C_Direction_Transmitter);
}while(!(I2C_ReadRegister(EEPROM_I2Cx, I2C_Register_SR1) & 0x0002));
/* Clear AF flag */
I2C_ClearFlag(EEPROM_I2Cx, I2C_FLAG_AF);
/* STOP condition */
I2C_GenerateSTOP(EEPROM_I2Cx, ENABLE);
}
/**
* @brief Basic management of the timeout situation.
* @param errorCode：错误代码，可以用来定位是哪个环节出错.
* @retval 返回0，表示IIC读取失败.
*/
static uint32_t I2C_TIMEOUT_UserCallback(uint8_t errorCode)
{
/* Block communication and all processes */
EEPROM_ERROR("I2C 等待超时!errorCode = %d",errorCode);
return 0;
}
#define EEP_Firstpage 0x00
uint8_t I2c_Buf_Write[256];
uint8_t I2c_Buf_Read[256];
uint8_t I2C_Test(void);
/**
* @brief 主函数
* @param 无
* @retval 无
*/
int main(void)
{
LED_GPIO_Config();
LED_BLUE;
/* 串口初始化 */
USART_Config();
printf("\r\n 这是一个I2C外设(AT24C02)读写测试例程 \r\n");
/* I2C 外设初(AT24C02)始化 */
I2C_EE_Init();
printf("\r\n 这是一个I2C外设(AT24C02)读写测试例程 \r\n");
//EEPROM 读写测试
if(I2C_Test() ==1)
{
LED_GREEN;
}
else
{
LED_RED;
}
while (1)
{
}
}
/**
* @brief I2C(AT24C02)读写测试
* @param 无
* @retval 正常返回1，异常返回0
*/
uint8_t I2C_Test(void)
{
uint16_t i;
printf("写入的数据\n\r");
for ( i=0; i<=255; i++ ) //填充缓冲
{
I2c_Buf_Write[i] = i;
printf("0x%02X ", I2c_Buf_Write[i]);
if(i%16 == 15)
printf("\n\r");
}
//将I2c_Buf_Write中顺序递增的数据写入EERPOM中
I2C_EE_BufferWrite( I2c_Buf_Write, EEP_Firstpage, 256);
EEPROM_INFO("\n\r写成功\n\r");
EEPROM_INFO("\n\r读出的数据\n\r");
//将EEPROM读出数据顺序保持到I2c_Buf_Read中
I2C_EE_BufferRead(I2c_Buf_Read, EEP_Firstpage, 256);
//将I2c_Buf_Read中的数据通过串口打印
for (i=0; i<256; i++)
{
if(I2c_Buf_Read[i] != I2c_Buf_Write[i])
{
EEPROM_ERROR("0x%02X ", I2c_Buf_Read[i]);
EEPROM_ERROR("错误:I2C EEPROM写入与读出的数据不一致\n\r");
return 0;
}
printf("0x%02X ", I2c_Buf_Read[i]);
if(i%16 == 15)
printf("\n\r");
}
EEPROM_INFO("I2C(AT24C02)读写测试成功\n\r");
return 1;
}