XM125 (SEN-24540) — No serial output with Exploration Server firmware on Mac

Sensors
1

Hi,

I purchased the XM125 board (SEN-24540). Using it on macOS Apple Silicon with Exploration Tool v7.17.6.

Board powers on, PWR LED solid, port shows as /dev/tty.usbserial-10. I flashed acc_exploration_server_a121.bin using both the Exploration Tool and STM32CubeProgrammer. CubeProgrammer confirms download and verification successful.

After reset, the board produces zero bytes on serial. Tested all baud rates 9600-921600, flow control off, auto-connect off. Exploration Tool gives “recv timeout” on every connect attempt. RST button causes no LED blink or change.

Bootloader mode works fine — CubeProgrammer connects and flashes without issues.

Questions:

  1. Does the Exploration Server firmware work with this board on Mac, or only with the XE125?

  2. Could the CH340 UART routing be incompatible with the Exploration Server firmware?

I spoke to Joelle on Amazon and she directed me here.

Thanks

2

  1. Looks like just Linux/Windows GitHub - acconeer/acconeer-python-exploration: Acconeer Exploration Tool · GitHub

  2. I’d sooner suspect the macOS security’s opinion of ch340 being the issue…if you don’t have a compatible PC around you might be able to try using dual-boot?

3

While troubleshooting, I modified the Option Bytes in STM32CubeProgrammer. I unchecked nSWBOOT0 to try and force hardware boot control. Since applying that change, I am getting a persistent “Timeout error occurred” and “Verify boot configuration” whenever I try to connect via UART.

  • I have tried the “Force-Connect” sequence (holding BOOT, tapping RST). Is there a specific timing or hardware jumper on the XM125 required to override the nSWBOOT0 = 0 state when using a Mac/CH340 setup.
  • If UART is permanently locked out due to the Option Byte change, will an ST-Link V2 via the SWD pins (GPIO0/GPIO1) allow me to force-reset the Option Bytes?
    Any guidance on getting this board back to a programmable state would be greatly appreciated!

Thanks,

Upagna

4

The main thing I’m sure of is that the baud rate has to be 115200; unfortunately we haven’t delved much into anything deeper…

I tried searching the Acconeer forums for ‘nSWBOOT0’ and it returned 0 results so I think you might be in uncharted territory - it’s probably worth creating a similar thread and/or submitting a ticket to their support

If you do find a workaround/solution please update this thread with your findings :slight_smile: