Get usable serial data from your cheap RFID readers!
- Uses Teensy 2.0 (since there is a USB serial and a hardware serial)
- Reads and converts raw data into the card's 10 digit ID
- Outputs the data into the serial (separated by newlines)
I recently bought one of those affordable (~US$10) chinese RFID readers. Unfortunately the device only outputs to USB (appears as a keyboard). I wanted the output via the serial port as it was inconvenient that the RFID reader hijacks your keyboard everytime a card is scanned, hence I created this project.
Using a logic analyser, I noticed that the pin labeled TX sends a serial output (bit rate: 9600) when a card is scanned. The format is as follows
[card digit] [240] [card digit]
repeated 10 times
I am not sure what the format for encoding the number is. However, since the character space should only span [0-9], I chose to decode it via a lookup table. Please note that this table is incomplete - help would be appreciated! (see caveats)
Your RFID reader must be similar or exactly the same as mine - this was the one I purchased. On the board, there should be a few test points. The one we are interested in is the serial TX (refer to image)
- Connect the TX pin from the reader to the RX pin of your Teensy (Pin 7/D2)
- Connect the RFID board's ground to your Teensy's ground
- Upload the sketch using Teensyduino
To prevent keystrokes being sent to the computer while supplying power, I believe it is possible to tape the USB data lines, leaving only 5V and GND
- The first digit is occassionally not sent (check whether the output's
length == 10) - The digits
4,7,8are not implemented! It would be great if someone has a RFID card with those digits and can help add them!
MIT