SD card reading and writing module can operate on SD card

SD card reading/writing module means reading and writing SD card / TF card with single chip microcomputer. SD card is a low-voltage flash memory product with two standard operation modules, MMC and SPI, respectively. For the MMC operation mode, the reading and writing speed is fast, and has many control signal lines, so the operation is complicated. For the SPI operation module, the speed is slow, and has fewer lines, so the operation is relatively simple.

Content

1 Overview 2 Technical Background 3 Technical Specifications 4 operation functions 5 pin definitions 6 operation commands 7 Application Areas 8 Development Kits

1.Overview

SD card reading/writing module

The SD card reading and writing module has a built-in file system and can directly read and write files. It can be used in single-chip microcomputer to realize mass capacity storage solution. With module, single-chip microcomputer can directly perform standard file system operations such as directory traversal, directory creation, directory deletion, file creation, file deletion, file modification, and card formatting, without knowing the internal storage structure of the SD card and the implementation details of the file system.

Especially, since SD cards has become more popular in our lives.with the popularity of SD cards in life, it has become a trend for embedded systems to integrate the functions of reading and writing SD cards into the system.

2.Technical Background

With the development of technology, it has become a common requirement for devices to use SD cards as storage devices. Due to limitation in resources, normally, traditional single-chip microcomputers cannot provide file system, thus cannot read and write files in the SD card. Using this module, the single-chip microcomputer but can directly operate files in the SD card without using file system, so it can launch stable products in the shortest time, avoid research and development risks to the greatest extent, and save research and development costs.

3.Technical Specifications

1. Support standard FAT file system, the SD card operated by the module can be directly inserted into the computer to read and write.

2. The module has a built-in Micro SD card slot, users can also expand other memory card slots by themselves. It can support various types of SD and MMC cards.

3. The module communicates with the single-chip microcomputer as a SPI slave, and the maximum speed of the SPI bus can reach 4M bps. The speed of which it reads SD card files can be up to 128K bytes/sec, and the speed of which it writes SD card files can be up to 64K bytes/sec.

4. The module supports SD card with a capacity of 2G Bytes. If the SD card capacity exceeds 2G, the card will be used as a 2G card.

5. its size is 50mm*20mm, the 2.54mm pitch universal pin header makes it easy to integrate.

4.Operation Function

1. check the total capacity and remaining space of the SD card, check other card management operations like SD card formatting.

2. Directory management operations such as create a directory, delete a directory, enter a directory, and return to the root directory.

3. File management operations such as create files, delete files, open files, and close files.

4. File reading and writing operations such as read files, write files, clear files, and modify the current position of files.

5. Other maintenance operations such as detect whether the SD card exists, notify the current time, query the module firmware version number.

These functions are sufficient for reading and writing files in the SD card, and the requirements for the single-chip microcomputer that perform these operations are not high, and all ram byte that exceeds 32K bytes can use this module to complete the reading and writing of the SD card.

5.Pin Definition

Pin number	Pin name	direction	Function description
1	RST#	input	Module reset
2	SD_DO	output	Data output of external memory card
3	SD_DET	input	Data input of external memory card
4	SD_CLK	output	Clock signal of external memory card
5	SD_DI	input	Data input of external memory card
6	SD_CS	output	Chip select signal of external memory card
7	V33	input	3.3V power
8	BZ	output	Module busy indication
9	SCS	input	Chip select signal of SPI interface
10	RXD	input	Data input of debug serial port
11	SCK	input	Clock signal of SPI interface
12	TXD	output	Data output of debug serial port
13	SDI	input	Data input of SPI interface
14	INT#	Output	Data ready indication
15	SDO	output	Data output of SPI interface
16	NC		Reserve
17	WAKE_UP	input	Wake
18	NC		Reserve
19	GND	input	Power ground
20	STA	output	Low power indication

6.Operation command

Order		Name	Explanation
CHECK_EXIST		Detect module and SD card	Test whether the communication with the SD card module is normal, and whether SD card has been inserted into the SD card module.
GET_DISK_SIZE		Check SD card capacity	Acquire information about SD card capacity and free space.
DISK_FORMAT		Format SD card	Format the SD card
GET_DIR_FIRST		Query the first directory item	Get the first directory entry in the current directory
GET_DIR_NEXT		Query next directory item	Get the next target item in the current directory
MAKE_DIR		Create directory	Create a subdirectory in the current directory
REMOVE_DIR		Delete directory	Delete a subdirectory in the current directory
ENTER_DIR		Enter directory	Enter a subdirectory in the current directory
BACK_TO_ROOT		Back to root	Go back to the root from current directory
MAKE_FILE		Create file	Create a file in the current directory
REMOVE_FILE		Delete File	Delete a file in the current directory
FILE_OPEN	Open File			Open a file in the current directory
FILE_CLOSE	Close file			Close an open file
FILE_GET_LEN	Query file length			Query the length of an open file
FILE_READ	Read file content			Read the contents of an open file (continuously read)
FILE_CLEAR	Empty file contents			Empty the contents of an open file
FILE_APPEND	Append file content			Append to the end of an open file
RENAME_DIR	Change the name of directory			Change the name of a subdirectory under the current directory
NOTICE_CUR_TIME	Update time			Update the current real time of the module
FILE_SEEK	File location			Move the current reading position of an open file
ENTER_SLEEP	Enter sleep mode			Let the module go into the power consumption state

7.Application field

· Desktop instruments, portable instruments, and electronic medical instruments (sphygmomanometer, blood glucose meter, blood lipid meter, cardiomotor, etc.)

· Sports equipment (treadmills, swing machines, etc.)

· Car dash camera

· Electronic system parameter setting (equipment for temperature control, travel control, etc.)

· CNC automation equipment (program access setting)

· Data collection

8.Development Kit

DSM-100 SD card reading and writing module 51 single-chip microcomputer development boar

The development board is implemented by STC89C52, a typical microcontroller in the 8051 series, and shows how to implement large-capacity data storage on a low-profile microcontroller.

Connect the development board to the computer with a USB cable, and the computer will recognize the development board as a serial device. (If it cannot be recognized, you need to install driver)

Use the serial port debugging tool (such as HyperTerminal) on the computer, set the serial port parameters to “9600bit/s baud rate, 8 data bits, no parity, 1 stop bit”, and then you can enter the command place of the development board.

At the command place, type “help” to get help. Enter other commands to query firmware version number, query card capacity, format card, create directory, delete directory, traverse directory, create file, delete file, read file, write file, and other operations.

Provide the source code development package required for secondary development, and users can use it in their own products with a little porting.