FRDM-IMX95: No Serial Output when Booting from SD Card (Pre-installed eMMC Boot Works Perfectly

[Magnus98]

Hello NXP Community,

I am mechanical and electrical engineering background, and this is my first time diving deep into complex System-on-Chips (SoCs) and embedded Operating Systems.

For my project, I am using the FRDM-IMX95 development board. My ultimate goal is to run two operating systems in parallel using an IPC (Inter-Process Communication) framework.

The board arrived with a pre-installed Linux image on the internal eMMC. This works flawlessly out of the box, and I get full serial output logs in my terminal monitor program.

Now, I am trying to follow the official Getting Started Guide to flash the standard Linux BSP image onto a microSD card using UUU (Universal Update Utility) on a Windows host machine.

According to the Windows command prompt, the UUU flashing process completes with a "SUCCESS" status. I used the following standard command layout: ".\uuu.exe -b sd_all imx-boot-imx95-15x15-lpddr4x-frdm-sd.bin-flash_all imx-image-full-imx95evk.wic"

The Problem: After successful flashing, I turn off the board and configure the physical boot switches for SD Boot Mode by setting SW1 [1:2] to 11 (ON / ON). When I power the board back on, the serial monitor remains completely blank. There is absolutely no text output or hardware initialization visible.

1. Do I have a fundamental misunderstanding of how the boot chain works here? According to the i.MX Linux User's Guide, the .wic image contains all four essential pieces, including the bootloader image (U-Boot). Shouldn't I at least see the initial U-Boot SPL sequence appearing on my serial monitor, since the basic hardware configuration blocks should be read from the card?

Any insights, common pitfalls for beginners on this specific FRDM variant, or hidden switch requirements would be highly appreciated!

Best regards

[Oswalag]

Hello, 

I'm testing on my side to share the exact steps for you, I will update soon. 

[Magnus98]

Thank you for looking into this and testing it on your end! I appreciate the help and look forward to your update.

[Oswalag]

You have the issue because you are trying to flash to the SD card with the uuu tool, it is made to flash the emmc, if you want to flash the sd card you have to perform the following command in a linux host machine. 

$ sudo dd if=<image_name>.wic of=/dev/sdx bs=1M && sync

To identify the device node assigned to the SD/MMC card, carry out the following command:

$ cat /proc/partitions
major minor #blocks name
8 0 78125000 sda
8 1 75095811 sda1
8 2 1 sda2
8 5 3028221 sda5
8 32 488386584 sdc
8 33 488386552 sdc1
8 16 3921920 sdb
8 18 3905535 sdb1