UART Communication Between Nucleo-L053R8 and Chafon RFID Reader IC

Navya · ‎2025-10-14

Hi everyone,

I'm currently working on a project where I need to establish UART communication between an STM32L053R8T6 Nucleo board and a Chafon RFID reader IC. The goal is to send commands from the STM32 to the reader and receive tag data in response.

Here's what we've done so far:

Hardware setup:
- STM32L053R8T6 Nucleo board
- Chafon reader IC (connected via UART)
- Power and ground lines are properly connected
- TX/RX lines are cross-connected (STM TX → Reader RX, STM RX ← Reader TX)

Software setup:
- Using STM32CubeIDE with HAL drivers
- UART initialized at 115200 baud (default for Chafon)
- Basic transmit/receive functions implemented using HAL_UART_Transmit and HAL_UART_Receive

- We're sure about the exact command format expected by the Chafon reader (e.g., start/stop bytes, checksum) but
the reader doesn’t seem to respond to our test commands.

- All the connections and UART ports are properly verified.

Questions

Has anyone successfully interfaced a Chafon reader or any other RFID reader module with STM32 via UART from the scratch ?
Would DMA or interrupt-based UART be more reliable for this kind of communication?
Any sample code or reference projects would be greatly appreciated!

Andrew Neil · ‎2025-10-15

Before adding the unknowns of this RFID reader, have you verified your STM32 UART Comms against a PC terminal?

Similarly, have you verified your understanding of the RFID reader's comms by connecting it to a PC terminal, and testing manually?

These are always key first steps for developing any UART-based interface!

Tips on debugging serial comms.

PS:

@Navya wrote:
- STM32L053R8T6 Nucleo board!

Are you sure that there's nothing on the Nucleo board which would interfere with your UART connection?

eg, you would need to disconnect the ST-Link's VCP before using that connection to your external reader...

How to write your question to maximize your chances to find a solution

PPS:

@Navya wrote:
Chafon RFID reader IC. !

You mean this "Chafon": https://www.chafon.com/ ?

Which chip?

@Navya wrote:
3. Any sample code or reference projects would be greatly appreciated!

You should ask Chafon that question - it's their product.

https://www.chafon.com/Contact

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

Navya · ‎2025-10-15

Hi,

@Andrew Neil wrote:
Before adding the unknowns of this RFID reader, have you verified your STM32 UART Comms against a PC terminal?
Similarly, have you verified your understanding of the RFID reader's comms by connecting it to a PC terminal, and testing manually?

I didn't understand what you meant by verifying against PC terminal. I am just a beginner and it would be helpful if you could provide more details on the comment.

Tips on debugging serial comms.

PS:
@Navya wrote:
- STM32L053R8T6 Nucleo board!
Are you sure that there's nothing on the Nucleo board which would interfere with your UART connection?
eg, you would need to disconnect the ST-Link's VCP before using that connection to your external reader...
The UART pins in the nucleo board are already verified and is working , but when connected to CHAFON module, we are not getting any response
How to write your question to maximize your chances to find a solution

PPS:

@Navya wrote:
Chafon RFID reader IC. !
You mean this "Chafon": https://www.chafon.com/ ?
Which chip?
CHAFON MU-910 M RFID Reader Module

@Navya wrote:
3. Any sample code or reference projects would be greatly appreciated!
You should ask Chafon that question - it's their product.
We were asking for any sample projects on establishing UART communication with RFID reader modules similiar to CHAFON
https://www.chafon.com/Contact