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

Andrew Neil · ‎2025-10-15

@Navya wrote:
I didn't understand what you meant by verifying against PC terminal.

Connect your STM32 to a PC via a suitable interface (eg, USB-to-UART cable)

Use a serial terminal program such as TeraTerm on the PC to send stuff to your STM32, and receive stuff from your STM32.

This is how you check that your STM32 stuff is working.

@Navya wrote:
I am just a beginner and it would be helpful if you could provide more details on the comment.

As a beginner, maybe start here with the basics.

See here for more ST learning resources.

@Navya wrote:
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

So what UART pins are you using?

If you want to use the same pins used by the ST-Link's VCP, you will need to break those connections

Show a schematic of your connections.

Again, please see: How to write your question to maximize your chances to find a solution

@Navya wrote:
CHAFON MU-910 M RFID Reader Module

You mean this: https://www.chafon.com/productinfo/1069984.html ?

It's always helpful to give a link - so people can be sure exactly what you're referring to.

@Navya wrote:
We were asking for any sample projects on establishing UART communication with RFID reader modules similiar to CHAFON

A UART neither knows nor cares what it is connected to - it just sends & receives bytes (characters).

So, once you can send & receive bytes between your STM32 and PC terminal, that it will work with any other UART-based device.

You can find UART examples for STM32 in STM32CubeIDE ...

PS:

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.