Serial UART to USB Pen Drive

Easily manage writing, reading files & directories on USB Pen Drive, from simple to use DOS like commands with serial interface.

Product Code 1307

Available We dispatch same day if ordered by 1PM (excluding holidays), then courier usually takes 2-5 days.
Quantity Pricing
Quantity :
Price (Discount%)
1-9 :
Rs.1,650.00/- (0%)
10-24 :
Rs.1,567.50/- (5%)
25-49 :
Rs.1,534.50/- (7%)
50-99 :
Rs.1,501.50/- (9%)
100-249 :
Rs.1,485.00/- (10%)
250-499 :
Rs.1,468.50/- (11%)
500-999 :
Rs.1,435.50/- (13%)
1000+ :
Rs.1,402.50/- (15%)


Serial UART to USB Pen Drive
Sunrom Product Code for Ordering:

Simple Commands like DOS to read/write files.

Status LEDs

  • Board has three LEDs
  • PWR - Green LED indicate that board is getting power
  • ERR - Red LED indicate any error like USB Drive not found or its unmounted
  • STS - Yellow LED can be OFF(No Drive) or ON(Drive inserted) or Blink(File Write Mode)

When USB Drive is inserted, it automatically mounts and red error led will switch off and yellow will come on.


Interface/Power Pins (4x)


Pin Name




Ground pin



Provide regulated +5V DC voltage to this pin for board operation. Board has LM1117-3.3V regulator to power all parts.

3 TX-OUT Outgoing Serial data for 3-5V UART. Typically connected to RXD pin of microcontroller or MAX232 or USB-TTL.

Incoming serial data at 5V or 3V level. If your data source is microcontroller, then you can connect its TXD pin to RX-IN of the board directly. If your data is at RS232 level data is use a MAX232 to convert that data to 5V UART suitable for board.

The board does not interpret the incoming data format, It can be any format, it just takes and writes to file. It is only considering baud rate of incoming data. It should be correctly set as per board configuration to write properly.

Detect Output pins (2x)


Pin Name




Ground pin



Interrupt signal output for microcontroller to detect if a USB Drive is inserted or not. If inserted this signal is LOW level. If there is no drive, then the DET level is high.


Testing with PuTTY

Its recommended and easy to test first with PC before moving to microcontroller interfacing.

Connect the board using USB-TTL or MAX232 to PC.

Download PuTTY to test, Although you can use any software supporting COM port communication, but PuTTY will be prefered since it will give you DOS like prompt. 

Start PuTTY and start using the board just like you do on DOS.


  • 8+3 format file names like DOS where 8 digit is maximum file name and DOT then upto 3 digit extension.
  • There should be no space in file or directory names
  • Only text files supported for writing/reading

Command List

There are basically three group of commands you can enter

  • Manage Files
  • Manage Directories
  • Setup Commands

NOTE: Enter Key (Decimal 13)  has to be sent after each command.

Manage Files


eg. CREATE test.txt
if file exists it is appended. 
if file does not exists it will be created.
Once you issue CREATE command,
you can start putting in data to file serially till you issue CTRL+Z(26 decimal) to save and close.

To create a file inside directory called 'dir' use like this eg. CREATE dir/test.txt

CTRL+Z(26 DEC) save and close the file opened, You can press CTRL+Z in terminal(PuTTY) or issue decimal 26 putchar from your microcontroller.
TYPE name

eg. type test.txt
show file content, 50 bytes at time
send CTRL+Z(26 DEC) to view next 50 bytes
send ESC(27 DEC) to terminate view and show prompt
end of file is marked with EOT(4 DEC)

To view a file inside directory called 'dir' use like this eg. TYPE dir/test.txt

DEL name delete file with 'name' eg. DEL test.txt
delete file inside 'dir' eg. DEL dir/test.txt
REN old new rename file/dir eg. REN DIR1 DIR2  or REN test.txt new.txt

Manage Directories

DIR list all files & dirs
DIR filter

list with filter(?,*) eg. *.txt, D?.txt
? matches single character
* matches multiple characters

MD name make directory of 'name' eg. MD dir1
RD name remove directory of 'name' eg. RD dir1

Setup Commands

? Show Help
INF File System Type FAT12/FAT16/FAT32
EXIT Unmount Drive for removal, Recommended for safe eject.

Show Date Time of internal RTC
Used in timestamping file create/modify date
You need to set it once after power up, then it maintains internally.

DATE dd:mm:yyyy Set Date of internal RTC, on start up it defaults to 01-01-1980
TIME hh:mm:ss Set Time of internal RTC, on start up it defaults to 00:00:00

Setting Baud Rate

To configure your board on which baud rate it should log the data you need to create a simple text file on your card. It can be empty file without any content in it. If there is no file for baud rate configuration default baud rate of 9600 bps will be set. It supports following baud rates. You can insert the USB Pen dive in your PC's USB port to create an empty text file with particular name as below table or create using commands.

Note: In PC, some computer you cannot see file extensions. To see file extensions, you can open windows Explorer > Organize > Folder Options > View > UNCHECK (Hide Extensions for known file types)

Setup File Created on Pen Drive

Baud Rate Format (8-N-1)
8 Data byte, No Parity, 1 Stop byte

<No File> Default Baud rate will be 9600


























Reading Data on PC

To read/write files on your USB Drive using PC, you can also remove drive from board and insert into it PC's USB port. You can view the text files as well as baud rate configuration file which you have created.


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