Hello,
I am working with the ST67W61 WiFi module and NCP firmware provided in X-CUBE-ST67W61.
The firmware flashing process works correctly when using the reference setup:
- NUCLEO-U575ZI-Q
- X-NUCLEO-67W61M1 expansion board
However, the same flashing procedure fails on our custom board, which is designed based on the X-NUCLEO-67W61M1 schematics.
Issue observed:
During NCP flashing over UART, the process fails at handshake stage with the following error:
- "ack is b''"
- "CHIP IMG LOAD SHAKEHAND FAIL"
Observations:
- UART communication appears inactive (no response from module)
- Same firmware and flashing tool used
- Same COM port configuration verified
- Power supply is stable (3.3V confirmed)
- Issue is reproducible consistently on custom board
Connections replicated from reference design:
- CN6: 3V3, 5V, GND
- CN5: SPI (CLK, MOSI, MISO, CS)
- CN9: BOOT, CHIP_EN, SPI_RDY, UART TX/RX
Suspected area:
We suspect the issue may be related to:
- BOOT pin configuration during reset
- CHIP_EN / RESET sequencing
- UART interface or pin mapping
- Bootloader entry timing requirements
Request:
Could you please help clarify:
- Required BOOT pin state for entering flashing mode
- Correct RESET and CHIP_EN sequence for bootloader entry
- Any timing constraints for UART handshake
- Minimum hardware requirements for reliable flashing (pull-ups, pin states, etc.)
If needed, I can provide:
- Custom board schematics
- Pin mapping details
- Logic analyzer captures
Thank you.
