SDIO

SDIO Demo Code Support List

This chapter introduces the details of the SDIO demo code.

SDIO Demo for Read and Write

The description of SDIO demo code 1 is shown in the following table.

SDIO Demo Code 1 Description
Demo 1	`sdio_demo.c`
Sample Purpose	Demonstrates how PC communicates with SD card.
Brief Introduction	This sample code demonstrates SD card read and write function. Read the data at the specified address of the SD card, and write the specified data to the SD card.
File Path	`sdk\src\sample\io_demo\sdio\sdcard\sdio_demo.c`
Function Entry	`sdio_demo()`
Supply Voltage	3.3V, check MCU config of voltage setting.
Group Pins	The specific group pins are shown in SDIO Group Pins in RTL87x3D and SDIO Group Pins in RTL87x3E.
Hardware Connection	Take RTL87x3D group0 as an example, shown in SDIO Demo Code Hardware Connection Diagram. The 6 pins of the SD card are respectively connected with group0 on EVB, and the VDD and GND pins of the SD card are connected with the VCC and GND pins on EVB.
Expected Result	Press the Reset button on the EVB, the string `sd_print_binary_data: buf` will be printed in Debug Analyzer. The last printed data buf is 0~FF+0~FF (512 bytes).

The hardware connection of SDIO demo code 1 is shown in the figure below.

../../../_images/SDIO_Hardware_Connection_Diagram.png — SDIO Demo Code Hardware Connection Diagram

The group pins of SDIO is shown in the tables below. RTL87x3EP is the same as RTL87x3E.

SDIO Group Pins in RTL87x3D
RTL87x3D	CLK	CMD	DAT0	DAT1	DAT2	DAT3
Group0 Pins	P1_2	P1_3	P1_4	P1_5	P1_6	P1_7
Group1 Pins	P4_2	P4_3	P4_4	P4_5	P4_6	P4_7

SDIO Group Pins in RTL87x3E
RTL87x3E	CLK	CMD	DAT0	DAT1	DAT2	DAT3
Group0 Pins	P5_0	P5_1	P5_2	P5_3	P5_4	P5_5
Group1 Pins	P6_0	P6_1	P6_2	P6_3	P6_4	P6_5

SDIO Demo for Filesystem

The description of SDIO demo code 2 is shown in the following table.

SDIO Demo Code 2 Description
Demo 2	`sdio_fs_demo.c`
Sample Purpose	Demonstrates how PC communicates with SD card by filesystem.
Brief Introduction	This sample code demonstrates SD card read and write function by filesystem. `FatFS_DirectoyDemo()` can write the data under the specified directory file of the SD card; `FatFS_Demo()` can write and read data directly to the SD card file.
File Path	`sdk\src\sample\io_demo\sdio\demo\sdio_fs_demo.c`
Function Entry	`SD_DemoCode()`
Supply Voltage	3.3V, check MCU config of voltage setting.
Group Pins	The specific group pins are shown in SDIO Group Pins in RTL87x3D and SDIO Group Pins in RTL87x3E.
Hardware Connection	Take RTL87x3D group0 as an example, shown in SDIO Demo Code Hardware Connection Diagram. The 6 pins of the SD card are respectively connected with group0 on EVB, and the VDD and GND pins of the SD card are connected with the VCC and GND pins on EVB.
Expected Result	Press the Reset button on the EVB. `FatFS_DirectoyDemo()`: String `FatFS_DirectoyDemo: write OK!` will be printed in Debug Analyzer. And check that the files in the BBpro directory of the SD card are written data. `FatFS_Demo()`: The string `FatFS_Demo: f_read: 0x31, 0x32, 0x33, read_len 1024!` will be printed in Debug Analyzer. And check that ‘Data.txt’ in the SD card is the written data.

SDIO Demo for SD Card Detection

The description of SDIO demo code 3 is shown in the following table.

SDIO Demo Code 3 Description
Demo 3	`sdio_card_detect_demo.c`
Sample Purpose	Demonstrates SD card detection by GPIO.
Brief Introduction	This sample code demonstrates the SD card detection function. Simulate SD card insertion and removal through GPIO.
File Path	`sdk\src\sample\io_demo\sdio\sdcard\sdio_card_detect_demo.c`
Function Entry	sdio_card_detect_demo()
Supply Voltage	3.3V, check MCU config of voltage setting.
Selected Card Detect Pin	`#define SD_CARD_DETECT_PIN P0_3`
Group Pins	The specific group pins are shown in SDIO Group Pins in RTL87x3D and SDIO Group Pins in RTL87x3E.
Hardware Connection	Take RTL87x3D group0 as an example, shown in SDIO Demo Code Hardware Connection Diagram. The 6 pins of the SD card are respectively connected with group0 on EVB, and the VDD and GND pins of the SD card are connected with the VCC and GND pins on EVB.
Expected Result	Connect P0_3 with GND on EVB, the string `gpio_isr_cb: card insert!` will be printed in Debug Analyzer. Remove P0_3 from GND, the string `gpio_isr_cb: card remove!` will be printed in Debug Analyzer.

Functional Overview

SDIO

Secure Digital Input and Output, defines a peripheral interface. SDIO card is an IO device that uses the SD bus and SD commands. The shape and interface of the SDIO card are compatible with the SD card, but it not only realizes the storage function, but also realizes other functions, such as Bluetooth, Wireless Fidelity, etc.
SDHC

SD host controller, the connection of SDHC and SD card is shown in SDHC and SD Card Connection Diagram. The host controls the internal operation of the SD card by reading/writing SDHC internal registers.
SDIO Transmission Mode

SPI mode, 1-bit mode (single-wire), 4-bit SD mode (four-wire). The pin definitions in different modes are shown in SDIO Pin Definitions in Different Modes.
SDIO Interface Definition (4-bit SD mode)
1. CLK
  
  Host to card clock signal.
2. CMD
  
  Bi-directional command/response signal.
3. DAT0-DAT3
  
  4 Bi-directional data signals.

Note

RTL87x3D, RTL87x3E, and RTL87x3EP support SDIO.
Please confirm whether SDIO pins are supported for the package before using SDIO.

SDIO Pin Definitions in Different Modes
Pins	4-Bit Mode	1-Bit Mode	SPI Mode
1	VCC	VCC	VCC
2	VSS1	VSS1	VSS1
3	VSS2	VSS2	VSS2
4	CLK	CLK	CLK
5	CMD	CMD	CS
6	DAT0	DAT0	DAT0
7	DAT1	RSV	DAT1
8	DAT2	RSV	RSV
9	DAT3/CD	CD	RSV

../../../_images/SDHC_and_SD_Card_Connection_Diagram.png — SDHC and SD Card Connection Diagram

Feature List

Support SD specifications V2.0.
Support only 2 group pins on EVB to communicate with SD card. For specific pins, please refer to SDIO Group Pins in RTL87x3D or SDIO Group Pins in RTL87x3E.
Support 1-bit and 4-bit SD bus width.
Support optional bus clock, 40MHz and 80MHz can only support in RTL87x3D.
Support multiple block and single block transfer, SDHC max block size is 512 Bytes.
High voltage SD card: operation voltage 3.3V.
Support GDMA transfer.
Support interrupt control.

SD Bus Protocol

The control on the SD bus is realized through CMD: The host initiates a request, and then the SD card responds to the request.
Data transfer format: Start bit 0, first MSB, then LSB, CRC check, end bit 1.
Data is transferred in the form of data blocks. SD Bus block read and write operation, as shown in SD BUS Multiple Block Read Operation and SD BUS Multiple Block Write Operation.

Take the SD Bus multi-block read operation as an example:

The host sends a multi-block read command.
The SD card sends a response.
The card starts sending data.
After each block is sent, return a CRC status.
The card transmits the next block data.
Until the host sends a stop command, the card responds.

../../../_images/SD_BUS_Multiple_Block_Read_Operation.png — SD BUS Multiple Block Read Operation

../../../_images/SD_BUS_Multiple_Block_Write_Operation.png — SD BUS Multiple Block Write Operation

Program Examples

Operation Flow

The codes below demonstrate the SD card initialization flow.

const T_SD_CONFIG    sd_card_cfg =
{
   .sd_if_type = SD_IF_SD_CARD,
   .sdh_group = GROUP_0,
   .sdh_bus_width = SD_BUS_WIDTH_4B,
   .sd_bus_clk_sel = SD_BUS_CLK_20M
};

/* SD config init */
sd_config_init((T_SD_CONFIG *)&sd_card_cfg);
/* Group pins PINMUX & PAD Config */
sd_board_init();
/* Initialize SD card peripheral */
sd_card_init();

The codes below demonstrate the SD card communication flow. For details, please refer to src\sample\io_demo\sdio\sdcard\sdio_demo.c.

static uint8_t *test_buf = NULL;
uint32_t sd_status = 0;

void sd_test(void)
{
   memset(test_buf, 0, sizeof(test_buf));
   /* Read the data at the specified address of the SD card */
   sd_status = sd_read(OPER_SD_CARD_ADDR, (uint32_t)test_buf, SINGLE_BLOCK_SIZE, BLOCK_NUM);

   if (sd_status != 0)
   {
      return ;
   }
   /*SD card print the binary data of test_buf */
   sd_print_binary_data(test_buf, SINGLE_BLOCK_SIZE * BLOCK_NUM);

   for (uint32_t i = 0; i < SINGLE_BLOCK_SIZE * BLOCK_NUM; i++)
   {
      test_buf[i] = i & 0xff;
   }
   sd_print_binary_data(test_buf, SINGLE_BLOCK_SIZE * BLOCK_NUM);
   /* Write the specified test_buf data to the SD card */
   sd_status = sd_write(OPER_SD_CARD_ADDR, (uint32_t)test_buf, SINGLE_BLOCK_SIZE, BLOCK_NUM);
}

The codes below demonstrate the SD card communication flow by filesystem.

For details, please refer to src\sample\io_demo\sdio\sdcard\demo\sdio_fs_demo.c.

void FatFS_Demo(void)
{
   uint32_t a = 1;
   uint32_t res = 0;
   const char driver_num = 0;

   /* Create workspace */
   res = f_mount(&fs, &driver_num, 1);

   /* Open file */
   res = f_open(&fdst, "Test.txt", FA_CREATE_ALWAYS | FA_WRITE);
   if (res != FR_OK)
   {
      //Open file failure, add error handle code here
      f_close(&fdst);
      return ;
   }

   res = f_open(&fsrc, "Data.txt", FA_OPEN_EXISTING | FA_READ);
   if (res != FR_OK)
   {
      //Open file failure, add error handle code here
      f_close(&fsrc);
      return ;
   }

   /* File operation */
   for (uint32_t i = 0; i < 1024; i++)
   {
      buffer[i] = i % 0x09 + 0x30;
   }
   buffer[1021] = 69;
   buffer[1022] = 69;
   buffer[1023] = 69;
   f_write(&fdst, buffer, 1024, &a);

   memset(buffer, 0, 1024);
   f_read(&fsrc, buffer, 1024, &a);

   /* Close file */
   f_close(&fsrc);
   f_close(&fdst);
}