Bringing up STM32MP257 & Debug

SCROGGYG · ‎2025-01-30

We have built a SBC using the 257EV as a reference in Altium. We are trying to use debug. We have created a ST14 connector to connect to a STLink3 using UART 2 as the debug serial port.

Is this possible, and should we use SWD or JTAG to debug the processor.

At present we are stuck at a flashing red led1. At present the DDR & GPU supplies haven't started on the PMIC, the remaining supplies are all present, as is the HSE clock.

Any thoughts would be appreciated.

PatrickF · ‎2025-01-30

Hi,

UART is a kind of minimum to allows console log.

SWD or JTAG is nice to have in case you want to debug low level SW (Cortex-M33, Linux driver, TF-A, etc...).

Have you build a customized image for your board (e.g. using Yocto) ?

Did you try to populate this image to your board ? Need at minimum USB3DRD device connection to a PC.
See how it is done using STM32MP257F-EV1: https://wiki.st.com/stm32mpu/wiki/Getting_started/STM32MP2_boards/STM32MP257x-EV1/Let%27s_start/Populate_the_target_and_boot_the_image
flashing red led at 5Hz mean the bootROM is waiting for a USB DFU connection (for flashload). Could be because no valid flash content detected or Boot pins are set to 0b0000 or 0b1111.

Regards.

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