The AK-SDFS-UART-B board allows you to read/write data from/to an SD card using a serial TTL port (UART). The board supports the FAT file system so the files can be read back from the SD on a PC/MAC.

Using a simple protocol (libraries included) you can read/write 4 files concurrently, in text or binary mode. Using only four wires (TX, RX, VCC and GND) you can read and write from the SD using very small microprocessors, even 8-bit ones. The baudrate can be adjusted from 9600 up to 460800 bps.

We have prepared a library that encapsulates the communication protocol and the source code can be downloaded. There is also an Arduino sketch demonstration available for download.

The AK-SDFS-UART-B is perfect to be used as a data logger, for sensors and debug information. It supports SD and SDHC cards.

We also have a micro SD version of this board.


  • Only four wires to get a working FAT File System
  • Powered from 3.3V external supply
  • All I/O pins are 5V tolerant
  • Operates on 4 files concurrently
  • RTC supported (time and date command has to be given at every power up)
  • Supports all file commands as Open, Create, Exist, Close, Write, Flush, Read, Size
  • Supports long file names
  • Supports directory tree listing
  • Commands to create and delete directories
  • Supports binary files
  • Uses a single and secure UART protocol. Source code examples are provided
  • Breadboard-ready
  • Supports firmware upgrade



Additional information

Weight 0.070 kg
Dimensions 20 × 22 × 20 mm


Verified Purchaser
2 years 5 months ago

Hello, I’m not using arduino with the uart sd card module. Can you give me an example of the raw serial strings to send to the module to create, open and write to a file. I don’t fully understand the user guide. Thanks

2 years 5 months ago

Hello. At page 9 of the user guide there is a full command with the format:

0x41 0x4B 0x01 0x00 0x00 0x0A … etc.

And the explanation of every part. If the manual is not clear, please point which part is not clear so we can explain it better.

If you are not using Arduino, we provide a C library for communicating with the board. This is the easiest way instead of reimplementing all the commands/packets. The explanation is at page 19 of the user guide.

The library can be found here (this is the same link on the product page)

If you need to post code, or for more detailed support, I suggest you to open a thread in the forum (which is better for support):

Thank you.

6 years 8 months ago

Are the tx-rx pins 5V tolerant? Or you have to use a voltage level shifter for interfacing with microcontrollers?

6 years 8 months ago

Hi. Sorry for the late reply. All the pins except for RESET are 5V tolerant.

8 years 4 months ago

What is the default baud rate, parity, stop bits communication settings to communicate with the AK-SDFS-UART-B – SD File System Through UART

8 years 4 months ago

Hi. The default settings are 9600, 8-N-1


Share this Product

AK-SDFS-UART-B – SD File System Through UART

The AK-SDFS-UART-B allows you to write and read files from a standard SD with FAT file system using an UART.


In stock

Category Tags , ,

Accepting all credit cards and wire transfers
Secure payments with Stripe and PayPal

Need help? Drop a line in our support forum.