UART communication between OpenMV board and STM32 Nucleo board

[vikas_sharma]

Hello everyone,

I am currently working on a project where I need to establish communication between the OpenMV H7 R2 board and the STM32 Nucleo-L476RG board. The goal is to transmit data generated by the OpenMV board (such as object detection results) to the STM32 board for further processing and control.

However, I am facing an issue where the STM32 Nucleo board is not receiving or properly interpreting the data sent from the OpenMV board. Below are some details of my setup:

• OpenMV H7 R2 Board: Configured to send data via UART (using uart.write() function).

• STM32 Nucleo-L476RG Board: UART interface configured using STM32CubeIDE (HAL library).

• Communication Protocol: UART (I have connected TX of OpenMV to RX of STM32 and common GND).

Problem: Despite configuring UART settings (baud rate, parity, stop bits, etc.) correctly on both boards, I am unable to receive any meaningful data on the STM32 side. There is no reception at all.

Steps I've Taken:

1. Verified baud rate settings match on both boards.

2. Checked wiring connections (TX-RX cross, common ground).

3. Tested UART reception on STM32 using a USB-to-Serial module — STM32 receives data correctly from PC, which suggests the STM32 UART setup is functional.

   Could anyone suggest what might be causing this issue? Are there any additional considerations when interfacing OpenMV UART with STM32 UART  Any example codes or configuration tips would be greatly appreciated.

   Thank you in advance!

[mƎALLEm]

Hello @vikas_sharma and welcome to the community,

---

@vikas_sharma wrote: Tested UART reception on STM32 using a USB-to-Serial module — STM32 receives data correctly from PC, which suggests the STM32 UART setup is functional.

---

As the reception worked well from Nucleo-L476RG board side with a PC, you didn't mention if you tested OpenMV H7 board with a PC + USB-to-Serial module to check if there is something went wrong with the transmission.

Did you do that?

[Ozone]

> Problem: Despite configuring UART settings (baud rate, parity, stop bits, etc.) correctly on both boards, I am unable to receive any meaningful data on the STM32 side. There is no reception at all.

As mentioned in similiar threads, did you verify the signal at the UART Rx pin of the L476 board ?
Use a scope or logic analyzer for that.

If the signal is there, your L476 firmware/UART setup is most probably not correct.

If it is not there, your wiring is incorrect, or the OpenMV board does not transmit at all.