23.1 实验内容

通过本实验主要学习以下内容：

• SDIO操作原理

• SD卡读写实现

23.2 实验原理

SD卡是一种主要以Nand Flash作为存储介质，具有体积小、数据传输速度快以及支持热插拔的优点。如今，已被广泛应用于数码相机、便携式移动设备以及手机等多种设备中。SD卡的驱动一般有SPI接口或SDIO接口，本例程介绍使用GD32F303的SDIO接口驱动SD卡的实现。

23.2.1 SD卡基础知识

SD卡:secure digital memory card是一种安全存储器件。属性是快闪存储器（flash eeprom），功能用来存储数据。

SD卡虽然是薄薄的一片，但是它并不是一个整体，而是由大量的集成电路组成。SD卡的内部结构如下图所示，主要由信号端子，接口控制器和存储区组成。

SD卡主要有两种模式，SD模式和SPI模式。不同模式下，接口定义不同。下面是SD卡的引脚。

两种模式的接口定义如下

SD模式中，主要由VCC(电源)，VSS(GND)，CLK（时钟，由主控提供)，CMD(命令)，DAT0-3(数据输入输出)，由6线制组成进行通信。SPI模式，主要采用4线制通信，除了电源地外，由MISO，MOSI，CLK，CS组成。下面简单介绍SD模式的操作。

要驱动SD卡工作，主要涉及两个步骤。第一个步骤是SD卡的识别过程。第二个步骤是对SD卡进行读写过程，即主机控制器和SD卡之间进行数据传输的过程。
要使SD卡能正常工作，一是要给SD卡供给稳定的电压，二是要SD卡按用户规定的方式工作。这两项工作的实现，都是主机控制器通过给SD卡发送控制命令来实现的。
主机（SDIO控制器）要驱动SD卡工作，要使用许多的命令，包括应用层命令ACMD 和 通用命令 CMD. 主机（SDIO控制器）把命令发送给SD卡，SD卡会作出回应，这里的回应叫做响应，响应命令分为6类，分别是R1、R1b、R2、R3、R6、R7。主机（SDIO控制器）给SD卡发送命令之后，SD卡会作出响应，响应中包含主机（SDIO控制器）需要的数据，这些数据有SD的信息，容量，和存储数据等等。上面已经提到了，SD卡工作，主要是识别和数据传输，它的识别过程有些复杂，写代码的时候，可以参考协议给的初始化流程图。数据传输包括读和写，单字节和多字节读写。下两节描述识别初始化流程图和数据读写时序图。

1、读写数据的时序图

SDIO与SD卡通信一般以数据块的形式进行传输，SDIO(多)数据块读操作，如下图所示。

SDIO(多)数据块写操作，如下图所示。

2、命令格式
SDIO所有的命令和响应都是在SDIO_CMD引脚上面传输的，命令长度固定为48位，SDIO命令格式如下表所示。

3、寄存器
SDIO控制器的寄存器，主要设置SDIO控制器和命令的索引与参数。SD卡有5个寄存器CID,RCA,CSD,SCR.OCR。SD卡的信息从SD卡寄存器中获取。

SD卡正常工作，就是根据SD卡初始化流程图，发送命令，收到回复，直到流程结束。传输数据，也是根据读写时序图，将要发送的数据放进命令中发送出去。

23.2.2 SDIO模块原理

SDIO为安全的数字输入输出接口，可以用于驱动SD卡、EMMC等，主要特征如下：

◼ MMC： 与多媒体卡系统规格书 V4.2 及之前的版本全兼容。有三种不同的数据总线模式：1 位(默认)、 4 位和 8 位；
◼ SD 卡： 与SD 存储卡规格版本2.0 全兼容；
◼ SD I/O： 与 SD I/O 卡规格版本 2.0 全兼容，有两种不同的数据总线模式： 1 位(默认)和4位；
◼ CE-ATA： 与 CE-ATA 数字协议版本 1.1 全兼容；
◼ 48MHz 数据传输频率和8 位数据传输模式；
◼ 中断和 DMA 请求；
◼ 完成信号使能和失能(CE-ATA)。

SDIO模块结构框图如下所示。主要包含两大部分：SDIO 适配器：由控制单元、命令单元和数据单元组成，控制单元管理时钟信号，命令单元管理命令的传输，数据单元管理数据的传输；AHB 接口：包括通过 AHB 总线访问的寄存器、用于数据传输的 FIFO 单元以及产生中断和DMA 请求信号。

SDIO模块可以实现对SD卡的完全驱动以及协议的实现，包括命令、响应等相关操作，本例程实现使用SDIO驱动SD卡初始化以及读写测试等相关操作，具体实现可以参考GD32F303用户手册以及代码解析等。

23.3 硬件设计

SD卡相关硬件电路如下图所示，实验板上具有SD卡卡座，信号线上有四根数据线，一根CMD命令线以及一根CLK时钟线，所有信号线通过10K电阻进行上拉，电源地信号线具有10uf以及100nf电容，SD卡插入时，金属接触点朝下插入。

23.4 代码解析

23.4.1 SDIO初始化配置函数

SDIO初始化配置在sd_io_init（）函数中，其中包括sd_init()初始化、sd_card_information_get（）SD卡信息获取、sd_card_select_deselect（）SD卡选择、sd_cardstatus_get（）SD卡状态获取、sd_bus_mode_config（）SD卡总线宽度配置以及sd_transfer_mode_config（）SD卡通信模式配置，历程中选择了4线查询模式。

C
sd_error_enum sd_io_init(void)
{
sd_error_enum status = SD_OK;
uint32_t cardstate = 0;
status = sd_init();
if(SD_OK == status){
status = sd_card_information_get(&sd_cardinfo);
}
if(SD_OK == status){
status = sd_card_select_deselect(sd_cardinfo.card_rca);
}
status = sd_cardstatus_get(&cardstate);
if(cardstate & 0x02000000){
//   printf("\r\n the card is locked!");
while (1){
}
}
if ((SD_OK == status) && (!(cardstate & 0x02000000)))
{
/* set bus mode */
status = sd_bus_mode_config(SDIO_BUSMODE_4BIT);
//        status = sd_bus_mode_config( SDIO_BUSMODE_1BIT );
}
if (SD_OK == status)
{
/* set data transfer mode */
//        status = sd_transfer_mode_config( SD_DMA_MODE );
status = sd_transfer_mode_config( SD_POLLING_MODE );
}
return status;
}

23.4.2 获取SD卡信息函数

获取SD卡信息的函数如下所示，card_info_get（）。

C
void card_info_get(void)
{
uint8_t sd_spec, sd_spec3, sd_spec4, sd_security;
uint32_t block_count, block_size;
uint16_t temp_ccc;
//printf("\r\n Card information:");
sd_spec = (sd_scr[1] & 0x0F000000) >> 24;
sd_spec3 = (sd_scr[1] & 0x00008000) >> 15;
sd_spec4 = (sd_scr[1] & 0x00000400) >> 10;
if(2 == sd_spec)
{
if(1 == sd_spec3)
{
if(1 == sd_spec4)
{
// printf("\r\n## Card version 4.xx ##");
}
else
{
//  printf("\r\n## Card version 3.0x ##");
}
}
else
{
// printf("\r\n## Card version 2.00 ##");
}
}
else if(1 == sd_spec)
{
// printf("\r\n## Card version 1.10 ##");
}
else if(0 == sd_spec)
{
// printf("\r\n## Card version 1.0x ##");
}

sd_security = (sd_scr[1] & 0x00700000) >> 20;
if(2 == sd_security)
{
//  printf("\r\n## SDSC card ##");
}
else if(3 == sd_security)
{
// printf("\r\n## SDHC card ##");
}
else if(4 == sd_security)
{
// printf("\r\n## SDXC card ##");
}

block_count = (sd_cardinfo.card_csd.c_size + 1)*1024;
block_size = 512;
//    printf("\r\n## Device size is %dKB ##", sd_card_capacity_get());
//    printf("\r\n## Block size is %dB ##", block_size);
//    printf("\r\n## Block count is %d ##", block_count);

if(sd_cardinfo.card_csd.read_bl_partial){
//  printf("\r\n## Partial blocks for read allowed ##" );
}
if(sd_cardinfo.card_csd.write_bl_partial){
// printf("\r\n## Partial blocks for write allowed ##" );
}
temp_ccc = sd_cardinfo.card_csd.ccc;
//printf("\r\n## CardCommandClasses is: %x ##", temp_ccc);
if((SD_CCC_BLOCK_READ & temp_ccc) && (SD_CCC_BLOCK_WRITE & temp_ccc)){
//  printf("\r\n## Block operation supported ##");
}
if(SD_CCC_ERASE & temp_ccc){
//  printf("\r\n## Erase supported ##");
}
if(SD_CCC_WRITE_PROTECTION & temp_ccc){
//  printf("\r\n## Write protection supported ##");
}
if(SD_CCC_LOCK_CARD & temp_ccc){
//   printf("\r\n## Lock unlock supported ##");
}
if(SD_CCC_APPLICATION_SPECIFIC & temp_ccc){
//   printf("\r\n## Application specific supported ##");
}
if(SD_CCC_IO_MODE & temp_ccc){
//  printf("\r\n## I/O mode supported ##");
}
if(SD_CCC_SWITCH & temp_ccc){
//  printf("\r\n## Switch function supported ##");
}
}

23.4.3 SD卡数据块写入函数

SD卡数据块写入函数如下所示，通过该函数可实现SD卡数据块的数据写入。

C
sd_error_enum sd_block_write(uint32_t *pwritebuffer, uint32_t writeaddr, uint16_t blocksize)
{
/* initialize the variables */
sd_error_enum status = SD_OK;
uint8_t cardstate = 0;
uint32_t count = 0, align = 0, datablksize = SDIO_DATABLOCKSIZE_1BYTE, *ptempbuff = pwritebuffer;
uint32_t transbytes = 0, restwords = 0, response = 0;
__IO uint32_t timeout = 0;

if(NULL == pwritebuffer){
status = SD_PARAMETER_INVALID;
return status;
}

transerror = SD_OK;
transend = 0;
totalnumber_bytes = 0;
/* clear all DSM configuration */
sdio_data_config(0, 0, SDIO_DATABLOCKSIZE_1BYTE);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOCARD);
sdio_dsm_disable();
sdio_dma_disable();

/* check whether the card is locked */
if(sdio_response_get(SDIO_RESPONSE0) & SD_CARDSTATE_LOCKED){
status = SD_LOCK_UNLOCK_FAILED;
return status;
}

/* blocksize is fixed in 512B for SDHC card */
if(SDIO_HIGH_CAPACITY_SD_CARD == cardtype){
blocksize = 512;
writeaddr /= 512;
}

align = blocksize & (blocksize - 1);
if((blocksize > 0) && (blocksize <= 2048) && (0 == align)){
datablksize = sd_datablocksize_get(blocksize);
/* send CMD16(SET_BLOCKLEN) to set the block length */
sdio_command_response_config(SD_CMD_SET_BLOCKLEN, (uint32_t)blocksize, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();

/* check if some error occurs */
status = r1_error_check(SD_CMD_SET_BLOCKLEN);
if(SD_OK != status){
return status;
}
}else{
status = SD_PARAMETER_INVALID;
return status;
}

/* send CMD13(SEND_STATUS), addressed card sends its status registers */
sdio_command_response_config(SD_CMD_SEND_STATUS, (uint32_t)sd_rca << SD_RCA_SHIFT, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_SEND_STATUS);
if(SD_OK != status){
return status;
}

response = sdio_response_get(SDIO_RESPONSE0);
timeout = 100000;

while((0 == (response & SD_R1_READY_FOR_DATA)) && (timeout > 0)){
/* continue to send CMD13 to polling the state of card until buffer empty or timeout */
--timeout;
/* send CMD13(SEND_STATUS), addressed card sends its status registers */
sdio_command_response_config(SD_CMD_SEND_STATUS, (uint32_t)sd_rca << SD_RCA_SHIFT, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_SEND_STATUS);
if(SD_OK != status){
return status;
}
response = sdio_response_get(SDIO_RESPONSE0);
}
if(0 == timeout){
return SD_ERROR;
}

/* send CMD24(WRITE_BLOCK) to write a block */
sdio_command_response_config(SD_CMD_WRITE_BLOCK, writeaddr, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_WRITE_BLOCK);
if(SD_OK != status){
return status;
}

stopcondition = 0;
totalnumber_bytes = blocksize;

/* configure the SDIO data transmission */
sdio_data_config(SD_DATATIMEOUT, totalnumber_bytes, datablksize);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOCARD);
sdio_dsm_enable();

if(SD_POLLING_MODE == transmode){
/* polling mode */
while(!sdio_flag_get(SDIO_FLAG_DTCRCERR | SDIO_FLAG_DTTMOUT | SDIO_FLAG_TXURE | SDIO_FLAG_DTBLKEND | SDIO_FLAG_STBITE)){
if(RESET != sdio_flag_get(SDIO_FLAG_TFH)){
/* at least 8 words can be written into the FIFO */
if((totalnumber_bytes - transbytes) < SD_FIFOHALF_BYTES){
restwords = (totalnumber_bytes - transbytes)/4 + (((totalnumber_bytes - transbytes)%4 == 0) ? 0 : 1);
for(count = 0; count < restwords; count++){
sdio_data_write(*ptempbuff);
++ptempbuff;
transbytes += 4;
}
}else{
for(count = 0; count < SD_FIFOHALF_WORDS; count++){
sdio_data_write(*(ptempbuff + count));
}
/* 8 words(32 bytes) has been transferred */
ptempbuff += SD_FIFOHALF_WORDS;
transbytes += SD_FIFOHALF_BYTES;
}
}
}

/* whether some error occurs and return it */
if(RESET != sdio_flag_get(SDIO_FLAG_DTCRCERR)){
status = SD_DATA_CRC_ERROR;
sdio_flag_clear(SDIO_FLAG_DTCRCERR);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_DTTMOUT)){
status = SD_DATA_TIMEOUT;
sdio_flag_clear(SDIO_FLAG_DTTMOUT);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_TXURE)){
status = SD_TX_UNDERRUN_ERROR;
sdio_flag_clear(SDIO_FLAG_TXURE);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_STBITE)){
status = SD_START_BIT_ERROR;
sdio_flag_clear(SDIO_FLAG_STBITE);
return status;
}
}else if(SD_DMA_MODE == transmode){
/* DMA mode */
/* enable the SDIO corresponding interrupts and DMA */
sdio_interrupt_enable(SDIO_INT_DTCRCERR | SDIO_INT_DTTMOUT | SDIO_INT_TXURE | SDIO_INT_DTEND | SDIO_INT_STBITE);
dma_transfer_config(pwritebuffer, blocksize);
sdio_dma_enable();

timeout = 100000;
while((RESET == dma_flag_get(DMA1, DMA_CH3, DMA_FLAG_FTF)) && (timeout > 0)){
timeout--;
if(0 == timeout){
return SD_ERROR;
}
}
while ((0 == transend) && (SD_OK == transerror)){
}

if(SD_OK != transerror){
return transerror;
}
}else{
status = SD_PARAMETER_INVALID;
return status;
}

/* clear the SDIO_INTC flags */
sdio_flag_clear(SDIO_MASK_INTC_FLAGS);
/* get the card state and wait the card is out of programming and receiving state */
status = sd_card_state_get(&cardstate);
while((SD_OK == status) && ((SD_CARDSTATE_PROGRAMMING == cardstate) || (SD_CARDSTATE_RECEIVING == cardstate))){
status = sd_card_state_get(&cardstate);
}
return status;
}

23.4.4 SD卡数据块读取函数

SD卡数据块读取函数如下所示。

C
sd_error_enum sd_block_read(uint32_t *preadbuffer, uint32_t readaddr, uint16_t blocksize)
{
/* initialize the variables */
sd_error_enum status = SD_OK;
uint32_t count = 0, align = 0, datablksize = SDIO_DATABLOCKSIZE_1BYTE, *ptempbuff = preadbuffer;
__IO uint32_t timeout = 0;

if(NULL == preadbuffer){
status = SD_PARAMETER_INVALID;
return status;
}

transerror = SD_OK;
transend = 0;
totalnumber_bytes = 0;
/* clear all DSM configuration */
sdio_data_config(0, 0, SDIO_DATABLOCKSIZE_1BYTE);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOCARD);
sdio_dsm_disable();
sdio_dma_disable();

/* check whether the card is locked */
if(sdio_response_get(SDIO_RESPONSE0) & SD_CARDSTATE_LOCKED){
status = SD_LOCK_UNLOCK_FAILED;
return status;
}

/* blocksize is fixed in 512B for SDHC card */
if(SDIO_HIGH_CAPACITY_SD_CARD == cardtype){
blocksize = 512;
readaddr /= 512;
}

align = blocksize & (blocksize - 1);
if((blocksize > 0) && (blocksize <= 2048) && (0 == align)){
datablksize = sd_datablocksize_get(blocksize);
/* send CMD16(SET_BLOCKLEN) to set the block length */
sdio_command_response_config(SD_CMD_SET_BLOCKLEN, (uint32_t)blocksize, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();

/* check if some error occurs */
status = r1_error_check(SD_CMD_SET_BLOCKLEN);
if(SD_OK != status){
return status;
}
}else{
status = SD_PARAMETER_INVALID;
return status;
}

stopcondition = 0;
totalnumber_bytes = blocksize;

/* configure SDIO data transmission */
sdio_data_config(SD_DATATIMEOUT, totalnumber_bytes, datablksize);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOSDIO);
sdio_dsm_enable();

/* send CMD17(READ_SINGLE_BLOCK) to read a block */
sdio_command_response_config(SD_CMD_READ_SINGLE_BLOCK, (uint32_t)readaddr, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_READ_SINGLE_BLOCK);
if(SD_OK != status){
return status;
}

if(SD_POLLING_MODE == transmode){
/* polling mode */
while(!sdio_flag_get(SDIO_FLAG_DTCRCERR | SDIO_FLAG_DTTMOUT | SDIO_FLAG_RXORE | SDIO_FLAG_DTBLKEND | SDIO_FLAG_STBITE)){
if(RESET != sdio_flag_get(SDIO_FLAG_RFH)){
/* at least 8 words can be read in the FIFO */
for(count = 0; count < SD_FIFOHALF_WORDS; count++){
*(ptempbuff + count) = sdio_data_read();
}
ptempbuff += SD_FIFOHALF_WORDS;
}
}

/* whether some error occurs and return it */
if(RESET != sdio_flag_get(SDIO_FLAG_DTCRCERR)){
status = SD_DATA_CRC_ERROR;
sdio_flag_clear(SDIO_FLAG_DTCRCERR);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_DTTMOUT)){
status = SD_DATA_TIMEOUT;
sdio_flag_clear(SDIO_FLAG_DTTMOUT);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_RXORE)){
status = SD_RX_OVERRUN_ERROR;
sdio_flag_clear(SDIO_FLAG_RXORE);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_STBITE)){
status = SD_START_BIT_ERROR;
sdio_flag_clear(SDIO_FLAG_STBITE);
return status;
}
while(RESET != sdio_flag_get(SDIO_FLAG_RXDTVAL)){
*ptempbuff = sdio_data_read();
++ptempbuff;
}
/* clear the SDIO_INTC flags */
sdio_flag_clear(SDIO_MASK_INTC_FLAGS);
}else if(SD_DMA_MODE == transmode){
/* DMA mode */
/* enable the SDIO corresponding interrupts and DMA function */
sdio_interrupt_enable(SDIO_INT_CCRCERR | SDIO_INT_DTTMOUT | SDIO_INT_RXORE | SDIO_INT_DTEND | SDIO_INT_STBITE);
sdio_dma_enable();
dma_receive_config(preadbuffer, blocksize);
timeout = 100000;
while((RESET == dma_flag_get(DMA1, DMA_CH3, DMA_FLAG_FTF)) && (timeout > 0)){
timeout--;
if(0 == timeout){
return SD_ERROR;
}
}
}else{
status = SD_PARAMETER_INVALID;
}
return status;
}

23.4.5 SD卡lock和unlock配置函数

SD卡lock和unlock配置函数如下所示。通过形参实现对SD卡的lock和unlock，若希望lock SD卡，lcokstate配置为SD_LOCK；若希望unlock SD卡，lockstate配置为SD_UNLOCK.

C
sd_error_enum sd_lock_unlock(uint8_t lockstate)
{
sd_error_enum status = SD_OK;
uint8_t cardstate = 0, tempbyte = 0;
uint32_t pwd1 = 0, pwd2 = 0, response = 0;
__IO uint32_t timeout = 0;
uint16_t tempccc = 0;

/* get the card command classes from CSD */
tempbyte = (uint8_t)((sd_csd[1] & SD_MASK_24_31BITS) >> 24);
tempccc = (uint16_t)((uint16_t)tempbyte << 4);
tempbyte = (uint8_t)((sd_csd[1] & SD_MASK_16_23BITS) >> 16);
tempccc |= (uint16_t)((uint16_t)(tempbyte & 0xF0) >> 4);

if(0 == (tempccc & SD_CCC_LOCK_CARD)){
/* don't support the lock command */
status = SD_FUNCTION_UNSUPPORTED;
return status;
}
/* password pattern */
pwd1 = (0x01020600|lockstate);
pwd2 = 0x03040506;

/* clear all DSM configuration */
sdio_data_config(0, 0, SDIO_DATABLOCKSIZE_1BYTE);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOCARD);
sdio_dsm_disable();
sdio_dma_disable();

/* send CMD16(SET_BLOCKLEN) to set the block length */
sdio_command_response_config(SD_CMD_SET_BLOCKLEN, (uint32_t)8, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_SET_BLOCKLEN);
if(SD_OK != status){
return status;
}

/* send CMD13(SEND_STATUS), addressed card sends its status register */
sdio_command_response_config(SD_CMD_SEND_STATUS, (uint32_t)sd_rca << SD_RCA_SHIFT, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_SEND_STATUS);
if(SD_OK != status){
return status;
}

response = sdio_response_get(SDIO_RESPONSE0);
timeout = 100000;
while((0 == (response & SD_R1_READY_FOR_DATA)) && (timeout > 0)){
/* continue to send CMD13 to polling the state of card until buffer empty or timeout */
--timeout;
/* send CMD13(SEND_STATUS), addressed card sends its status registers */
sdio_command_response_config(SD_CMD_SEND_STATUS, (uint32_t)sd_rca << SD_RCA_SHIFT, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_SEND_STATUS);
if(SD_OK != status){
return status;
}
response = sdio_response_get(SDIO_RESPONSE0);
}
if(0 == timeout){
return SD_ERROR;
}

/* send CMD42(LOCK_UNLOCK) to set/reset the password or lock/unlock the card */
sdio_command_response_config(SD_CMD_LOCK_UNLOCK, (uint32_t)0x0, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_LOCK_UNLOCK);
if(SD_OK != status){
return status;
}

response = sdio_response_get(SDIO_RESPONSE0);

/* configure the SDIO data transmission */
sdio_data_config(SD_DATATIMEOUT, (uint32_t)8, SDIO_DATABLOCKSIZE_8BYTES);
sdio_data_transfer_config(SDIO_TRANSMODE_BLOCK, SDIO_TRANSDIRECTION_TOCARD);
sdio_dsm_enable();

/* write password pattern */
sdio_data_write(pwd1);
sdio_data_write(pwd2);

/* whether some error occurs and return it */
if(RESET != sdio_flag_get(SDIO_FLAG_DTCRCERR)){
status = SD_DATA_CRC_ERROR;
sdio_flag_clear(SDIO_FLAG_DTCRCERR);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_DTTMOUT)){
status = SD_DATA_TIMEOUT;
sdio_flag_clear(SDIO_FLAG_DTTMOUT);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_TXURE)){
status = SD_TX_UNDERRUN_ERROR;
sdio_flag_clear(SDIO_FLAG_TXURE);
return status;
}else if(RESET != sdio_flag_get(SDIO_FLAG_STBITE)){
status = SD_START_BIT_ERROR;
sdio_flag_clear(SDIO_FLAG_STBITE);
return status;
}

/* clear the SDIO_INTC flags */
sdio_flag_clear(SDIO_MASK_INTC_FLAGS);
/* get the card state and wait the card is out of programming and receiving state */
status = sd_card_state_get(&cardstate);
while((SD_OK == status) && ((SD_CARDSTATE_PROGRAMMING == cardstate) || (SD_CARDSTATE_RECEIVING == cardstate))){
status = sd_card_state_get(&cardstate);
}
return status;
}

23.4.6 SD卡erase擦除操作函数

SD卡擦除操作函数如下，其形参为擦除起始地址以及结束地址。

C
sd_error_enum sd_erase(uint32_t startaddr, uint32_t endaddr)
{
/* initialize the variables */
sd_error_enum status = SD_OK;
uint32_t count = 0, clkdiv = 0;
__IO uint32_t delay = 0;
uint8_t cardstate = 0, tempbyte = 0;
uint16_t tempccc = 0;

/* get the card command classes from CSD */
tempbyte = (uint8_t)((sd_csd[1] & SD_MASK_24_31BITS) >> 24);
tempccc = (uint16_t)((uint16_t)tempbyte << 4);
tempbyte = (uint8_t)((sd_csd[1] & SD_MASK_16_23BITS) >> 16);
tempccc |= (uint16_t)((uint16_t)(tempbyte & 0xF0) >> 4);
if(0 == (tempccc & SD_CCC_ERASE)){
/* don't support the erase command */
status = SD_FUNCTION_UNSUPPORTED;
return status;
}
clkdiv = (SDIO_CLKCTL & SDIO_CLKCTL_DIV);
clkdiv += ((SDIO_CLKCTL & SDIO_CLKCTL_DIV8)>>31)*256;
clkdiv += 2;
delay = 120000 / clkdiv;

/* check whether the card is locked */
if (sdio_response_get(SDIO_RESPONSE0) & SD_CARDSTATE_LOCKED){
status = SD_LOCK_UNLOCK_FAILED;
return(status);
}

/* blocksize is fixed in 512B for SDHC card */
if (SDIO_HIGH_CAPACITY_SD_CARD == cardtype){
startaddr /= 512;
endaddr /= 512;
}

if((SDIO_STD_CAPACITY_SD_CARD_V1_1 == cardtype) || (SDIO_STD_CAPACITY_SD_CARD_V2_0 == cardtype) ||
(SDIO_HIGH_CAPACITY_SD_CARD == cardtype)){
/* send CMD32(ERASE_WR_BLK_START) to set the address of the first write block to be erased */
sdio_command_response_config(SD_CMD_ERASE_WR_BLK_START, startaddr, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_ERASE_WR_BLK_START);
if(SD_OK != status){
return status;
}

/* send CMD33(ERASE_WR_BLK_END) to set the address of the last write block of the continuous range to be erased */
sdio_command_response_config(SD_CMD_ERASE_WR_BLK_END, endaddr, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_ERASE_WR_BLK_END);
if(SD_OK != status){
return status;
}
}

/* send CMD38(ERASE) to set the address of the first write block to be erased */
sdio_command_response_config(SD_CMD_ERASE, (uint32_t)0x0, SDIO_RESPONSETYPE_SHORT);
sdio_wait_type_set(SDIO_WAITTYPE_NO);
sdio_csm_enable();
/* check if some error occurs */
status = r1_error_check(SD_CMD_ERASE);
if(SD_OK != status){
return status;
}
/* loop until the counter is reach to the calculated time */
for(count = 0; count < delay; count++){
}
/* get the card state and wait the card is out of programming and receiving state */
status = sd_card_state_get(&cardstate);
while((SD_OK == status) && ((SD_CARDSTATE_PROGRAMMING == cardstate) || (SD_CARDSTATE_RECEIVING == cardstate))){
status = sd_card_state_get(&cardstate);
}
return status;
}

23.4.7 主函数

SD卡主函数如下，可实现对SD卡的擦写读以及加锁解锁操作。

C
int main(void)
{
sd_error_enum sd_error;
uint16_t i = 5;

ifdef DATA_PRINT

uint8_t *pdata;

endif /* DATA_PRINT */

/* configure the NVIC, USART and LED */
nvic_config();

bsp_uart_init(&BOARD_UART);

/* initialize the card */
do{
sd_error = sd_io_init();
}while((SD_OK != sd_error) && (--i));

if(i){
printf("\r\n Card init success!\r\n");
}else{
printf("\r\n Card init failed!\r\n");
while (1){
}
}

/* get the information of the card and print it out by USART */
card_info_get();

/* init the write buffer */
for(i=0; i<512; i++){
buf_write[i] = i;
}

printf("\r\n\r\n Card test:");

/* single block operation test */
sd_error = sd_block_write(buf_write, 100*512, 512);
if(SD_OK != sd_error){

printf("\r\n Block write fail!");
while (1){
}
}else{
printf("\r\n Block write success!");
}
sd_error = sd_block_read(buf_read, 100*512, 512);
if(SD_OK != sd_error){
printf("\r\n Block read fail!");

while (1){
}
}else{
//printf("\r\n Block read success!");

ifdef DATA_PRINT

pdata = (uint8_t *)buf_read;
/* print data by USART */
printf("\r\n");
for(i = 0; i < 128; i++){
printf(" %3d %3d %3d %3d ", *pdata, *(pdata+1), *(pdata+2), *(pdata+3));
pdata += 4;
if(0 == (i + 1) % 4){
printf("\r\n");
}
}

endif /* DATA_PRINT */

}

/* lock and unlock operation test */
if(SD_CCC_LOCK_CARD & sd_cardinfo.card_csd.ccc){
/* lock the card */
sd_error = sd_lock_unlock(SD_LOCK);
if(SD_OK != sd_error){
printf("\r\n Lock failed!");
while (1){
}
}else{
printf("\r\n The card is locked!");
}
sd_error = sd_erase(100*512, 101*512);
if(SD_OK != sd_error){
printf("\r\n Erase failed!");
}else{
__NOP();
printf("\r\n Erase success!");
}

/* unlock the card */
sd_error = sd_lock_unlock(SD_UNLOCK);
if(SD_OK != sd_error){
printf("\r\n Unlock failed!");
while (1){
}
}else{
printf("\r\n The card is unlocked!");
}
sd_error = sd_erase(100*512, 101*512);
if(SD_OK != sd_error){
printf("\r\n Erase failed!");
}else{
printf("\r\n Erase success!");
}

sd_error = sd_block_read(buf_read, 100*512, 512);
if(SD_OK != sd_error){
printf("\r\n Block read fail!");
while (1){
}
}else{
printf("\r\n Block read success!");

ifdef DATA_PRINT

pdata = (uint8_t *)buf_read;
/* print data by USART */
printf("\r\n");
for(i = 0; i < 128; i++){
printf(" %3d %3d %3d %3d ", *pdata, *(pdata+1), *(pdata+2), *(pdata+3));
pdata += 4;
if(0 == (i + 1) % 4){
printf("\r\n");
}
}

endif /* DATA_PRINT */

}
}

/* multiple blocks operation test */
sd_error = sd_multiblocks_write(buf_write, 200*512, 512, 3);
if(SD_OK != sd_error){
printf("\r\n Multiple block write fail!");
while (1){
}
}else{
printf("\r\n Multiple block write success!");
}
sd_error = sd_multiblocks_read(buf_read, 200*512, 512, 3);
if(SD_OK != sd_error){
printf("\r\n Multiple block read fail!");

while (1){
}
}else{
printf("\r\n Multiple block read success!");

ifdef DATA_PRINT

pdata = (uint8_t *)buf_read;
/* print data by USART */
printf("\r\n");
for(i = 0; i < 512; i++){
printf(" %3d %3d %3d %3d ", *pdata, *(pdata+1), *(pdata+2), *(pdata+3));
pdata += 4;
if(0 == (i + 1) % 4){
printf("\r\n");
}
}

endif /* DATA_PRINT */

}

while (1){
}
}

23.5 实验结果

将SD卡读写实验例程烧录到红枫派开发板中，并在卡槽中插入SD卡，打开对应串口复位芯片，将会观察到SD卡相关操作结果。

红枫派开发板使用手册：‌​​⁣​⁤‬⁢‬⁤⁡‍​⁡‌⁡‍‍‬‍⁡⁣⁤‍‍​⁣‍‬​‍⁢​⁢⁣​‍⁤⁤‬‌‌⁡‌​GD32F303红枫派使用手册 - 飞书云文档 (feishu.cn)