21.1实验内容
通过本实验主要学习以下内容:
21.2实验原理
21.2.1AT24C16 EEPROM的工作原理
下图为AT24CXX系列EEPROM相关参数,由该图可知,AT24C16的存储容量为16Kbit,共2048字节,共128页,每页为16字节。
由下图可知,AT24C16由8块组成,每块256字节。
I2C开始信号后,第一个字节为器件地址,由1010+3位块地址+1位读写标志组成,3位块地址刚好可以表示8个块, 所以一次写完256字节,换到下一下块的时候,要重新更改器件地址。
AT24C16支持页写入模式,一次最多可支持写入16字节。主机每发送一个字节,24c16收到确认,内部地址递增(仅限低4bit,所以1次可写16字节)。
21.2.2IIC接口原理
GD32F30X系列MCU的I2C接口模块实现了I2C协议的标速模式,快速模式以及快速+模式,具备CRC计算和校验功能、支持SMBus(系统管理总线)和PMBus(电源管理总线),此外还支持多主机I2C总线架构,其主要特性如下:
◼并行总线至I2C总线协议的转换及接口;
◼同一接口既可实现主机功能又可实现从机功能;
◼主从机之间的双向数据传输;
◼支持7位和10位的地址模式和广播寻址;
◼支持I2C多主机模式;
◼支持标速(最高100 KHz),快速(最高400 KHz)和快速+模式(最高1MHz);
◼从机模式下可配置的SCL主动拉低;
◼支持DMA模式;
◼兼容SMBus 2.0和PMBus;
◼两个中断:字节成功发送中断和错误事件中断;
◼可选择的PEC(报文错误校验)生成和校验。
IIC模块结构框图如下所示。
21.3硬件设计
EEPROM硬件电路图如下所示,IIC引脚使用PB10和PB11引脚,SDA和SCL总线通过4.7K电阻上拉,且对地接30pf电容以及100欧姆串阻滤波。
21.4代码解析
21.4.1EEPROM初始化配置函数
EEPROM初始化配置函数如下,主要实现对IIC总线引脚配置以及IIC模块配置。
C void bsp_eeprom_init_AT24C16(void) { driver_i2c_init(&EEPROM_I2C); } void driver_i2c_init(typdef_i2c_struct *i2cx) { rcu_periph_clock_enable(i2cx->rcu_i2c_x); i2c_deinit(i2cx->i2c_x); driver_gpio_general_init(i2cx->i2c_scl_gpio); driver_gpio_general_init(i2cx->i2c_sda_gpio); /* I2C clock configure */ i2c_clock_config(i2cx->i2c_x, i2cx->frequency, I2C_DTCY_2); /* I2C address configure */ i2c_mode_addr_config(i2cx->i2c_x, I2C_I2CMODE_ENABLE, I2C_ADDFORMAT_7BITS, i2cx->slave_addr); /* enable I2C0 */ i2c_enable(i2cx->i2c_x); /* enable acknowledge */ i2c_ack_config(i2cx->i2c_x, I2C_ACK_ENABLE); } |
21.4.2EEPROM buf写入接口函数
EEPROM buf写入接口函数实现如下,通过该函数可实现对AT24C16任意地址的多字节写入。内部已根据地址和写入长度自动识别从机地址以及对应的块,然后写入正确的地址空间。
C EEPROM_STATE eeprom_buffer_write_AT24C16(uint8_t* p_buffer, uint16_t write_address, uint16_t number_of_byte) { uint8_t number_of_page = 0, number_of_single = 0, address = 0, count = 0; uint8_t deviceId; address = write_address % I2C_PAGE_SIZE; count = I2C_PAGE_SIZE - address; number_of_page = number_of_byte / I2C_PAGE_SIZE; number_of_single = number_of_byte % I2C_PAGE_SIZE; if(write_address+write_address>EEPROM_SIZE) { return EEPROM_ERROR; } /* if write_address is I2C_PAGE_SIZE aligned */ if(0 == address){ while(number_of_page--){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer,I2C_PAGE_SIZE) == DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C) == EEPROM_ERROR) { return EEPROM_ERROR; } write_address += I2C_PAGE_SIZE; p_buffer += I2C_PAGE_SIZE; } if(0 != number_of_single){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer, number_of_single)==DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C) == EEPROM_ERROR) { return EEPROM_ERROR; } } return EEPROM_SUCCESS; }else{ /* if write_address is not I2C_PAGE_SIZE aligned */ if(number_of_byte < count){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer, number_of_byte)==DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C)==EEPROM_ERROR) { return EEPROM_ERROR; } }else{ number_of_byte -= count; number_of_page = number_of_byte / I2C_PAGE_SIZE; number_of_single = number_of_byte % I2C_PAGE_SIZE; if(0 != count){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer, count)==DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C)==EEPROM_ERROR) { return EEPROM_ERROR; } write_address += count; p_buffer += count; } /* write page */ while(number_of_page--){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer, I2C_PAGE_SIZE)==DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C)==EEPROM_ERROR) { return EEPROM_ERROR; } write_address += I2C_PAGE_SIZE; p_buffer += I2C_PAGE_SIZE; } /* write single */ if(0 != number_of_single){ deviceId=(write_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((write_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_write(&EEPROM_I2C,deviceId,write_address,MEM_ADDRESS_8BIT,p_buffer, number_of_single)==DRV_ERROR) { return EEPROM_ERROR; } if(eeprom_wait_standby_state(&EEPROM_I2C)==EEPROM_ERROR) { return EEPROM_ERROR; } } } return EEPROM_SUCCESS; } } |
21.4.3EEPROM buf读取接口函数
EEPROM buf读取接口函数实现如下,通过该函数可实现对EEPROM任意地址的多字节数据读取,内部也对读取的地址进行自动识别从机地址。
C EEPROM_STATE eeprom_buffer_read_AT24C16(uint8_t* p_buffer, uint16_t read_address, uint16_t number_of_byte) { uint8_t rNum=0; //读取的数据长度 uint16_t lenLeft=number_of_byte;//剩余的数据长度 uint8_t deviceId;//读取的器件地址 if(read_address+number_of_byte>EEPROM_SIZE)//如果读取的长度加上读取地址超过了EEPROM的空间大小,则报错误 { return EEPROM_ERROR; } /*calculate the current read position to know how many word can read continully*/ rNum=16-read_address & 0x0F; if(rNum == 0) rNum=16; rNum = lenLeft>=rNum ? rNum : lenLeft;//剩余未读字节数如果大于rNum, 则读rNum个,如果小于rNum,则一次读完了 /*read the data from e2prom*/ while(lenLeft) { //这里计算页地址,当地址小于256时,右移8位会小于0,所以器件地址为基地址A1 //如果读取的地址大于256时,右移8位则不会小于0,所以器件地址为 基地址A1 | 3位页地址 deviceId=(read_address>>8)>0 ? (EEPROM_ADDR | (uint8_t)((read_address>>7)&0x0E)):EEPROM_ADDR ; if(driver_i2c_mem_poll_read(&EEPROM_I2C,deviceId,read_address,MEM_ADDRESS_8BIT,p_buffer,rNum)==DRV_ERROR) { // printf("i2c read error\r\n"); return EEPROM_ERROR; } read_address+=rNum;//已经读了rNum个了,所以地址后移rNum个 lenLeft-=rNum;//剩余未读数据减少rNum个 p_buffer+=rNum; rNum=lenLeft>16? 16 : lenLeft;//如果剩余大于16个,则下次再读16个,如果小于,则一次读完 } return EEPROM_SUCCESS; } |
21.4.4EEPROM读写实验主函数
EEPROM读写实验主函数如下所示。通过该实验实现对AT24C16任意地址256字节的写入、读取以及校验测试。
C int main(void) { uint16_t i; uint8_t i2c_buffer_write[BUFFER_SIZE]; uint8_t i2c_buffer_read[BUFFER_SIZE]; bsp_eeprom_init_AT24C16(); /* initialize i2c_buffer_write */ for(i = 0;i < BUFFER_SIZE;i++){ i2c_buffer_write[i]=i; // printf("0x%02X ",i2c_buffer_write[i]); // if(15 == i%16){ // printf("\r\n"); // } } if(eeprom_buffer_write_AT24C16(i2c_buffer_write,0x0153,BUFFER_SIZE)==EEPROM_SUCCESS) { __nop(); } if(eeprom_buffer_read_AT24C16(i2c_buffer_read,0x0153,BUFFER_SIZE)==EEPROM_SUCCESS) { __nop(); } /* compare the read buffer and write buffer */ for(i = 0;i < BUFFER_SIZE;i++){ if(i2c_buffer_read[i] != i2c_buffer_write[i]){ __nop(); // printf("0x%02X ", i2c_buffer_read[i]); // printf("Err:data read and write aren't matching.\n\r"); // return I2C_FAIL; } //printf("0x%02X ", i2c_buffer_read[i]); // if(15 == i%16){ // printf("\r\n"); // } } __nop(); // printf("I2C-AT24C02 test passed!\n\r"); while (1) { } } |
21.5实验结果
将本实验历程烧录到红枫派开发板中,运行后,可通过串口打印测试结果,可实现对于AT24C16任意地址写入、读取以及校验。
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