Issue booting the beagleplay if using UART0

We are using a beagleplay SBC for a project and I am having a strange issue. We are using the UART5 (on the mikrobus connector) and UART0 (the 3 pins coming out near the USB C connector) to communicate with a 2 microcontroller’s.

However If i attach our external board to the UART0 and do a reboot most of the time the beagle play doesn’t boot. I have checked the USER LED’s and I see they are all 00000. From this guide that seems to indicate a “Boot failure or R5 image not started up”.

Is there anything else I can check to debug why this boot failure is happening? Any suggestions on how to use UART0 and still have a reliable reboot?

We figured out a bit of a hack/clever workaround for this issue.

To give a bit more context we are running Zephyr RTOS on the micro-controller so we simply implemented a Zephyr Shell command named “U-Boot” and all it does is put our micro-controller to sleep for a short period of time, and don’t log anything to the UART. This allowed the the BeaglePlay time to boot and have exclusive access to UART0. Then once we are in the HLOS we are good to use UART0 to communicate with the micro-controller.

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