Hello NXP Support,
I am requesting help recovering an FRDM-i.MX93 board. The board consistently stops during early SPL boot immediately after “M33 prepare ok” and does not continue to BL31 or full U-Boot. UUU recovery also fails during SDPS boot with a timeout.
Board details:
Board: FRDM-i.MX93
SoC shown in serial log: 0xa1009300
LC shown in serial log: 0x2040010
PMIC: PCA9451A
DDR: 3733MTS
Typical serial output:
U-Boot SPL 2024.04+gde16f4f1722+p0 (Sep 02 2024 - 10:44:35 +0000)
SOC: 0xa1009300
LC: 0x2040010
PMIC: PCA9451A
PMIC: Over Drive Voltage Mode
DDR: 3733MTS
DDR: 3733MTS
M33 prepare ok
The same stop point also occurs with a rebuilt 2025 SPL:
U-Boot SPL 2025.04 (Apr 26 2026 - 16:21:54 +0000)
PMIC: PCA9451A
PMIC: Over Drive Voltage Mode
DDR: 3733MTS
DDR: 3733MTS
M33 prepare ok
Hardware setup used:
P1 = external power supply, tested with 45 W USB-C wall adapter
P16 = debug serial console
P13 = microSD card slot
P2 = USB-C connection for UUU / serial downloader mode
I also tested powering from a wall adapter instead of PC USB power. The behavior did not change.
Host systems tested:
Linux Mint / Ubuntu host
Windows host
UUU versions tested:
uuu 1.5.141
uuu 1.5.243
The main issue is that the board reaches SPL, initializes PMIC and DDR, and prints “M33 prepare ok”, then nothing else happens. It never reaches “Normal Boot”, “Trying to boot from BOOTROM”, “NOTICE: BL31”, or full U-Boot. This happens when booting from both SD and eMMC.
In USB Serial Downloader mode, the board is detected by UUU:
sudo ./uuu -lsusb
Connected Known USB Devices
Path Chip Pro Vid Pid BcdVersion
5:2 MX93 SDPS: 0x1FC9 0x014E 0x0001
However, UUU fails during SDPS boot. The command used was:
sudo ./uuu -V -b emmc_all imx-boot-imx93frdm-sd.bin-flash_singleboot imx-image-full-imx93frdm.rootfs.wic.zst
On Linux, the failure is:
Start Cmd:SDPS: boot -scanterm -f imx-boot-imx93frdm-sd.bin-flash_singleboot -scanlimited 0x800000
Fail HID(W):LIBUSB_ERROR_TIMEOUT
On Windows, the failure is:
Start Cmd:SDPS: boot -scanterm -f .\imx-boot-imx93frdm-sd.bin-flash_singleboot -scanlimited 0x800000
14%
Fail HID(W): LIBUSB_ERROR_TIMEOUT (-7)
This was tested on both Linux and Windows, with the same result.
Images tested:
I tested the official NXP FRDM-i.MX93 Rev 4.0 demo image package:
LF_v6.6.36-2.1.0_images_FRDM_4.0_IMX93
The boot image hash is:
7aba6102e5ec64add632cd6667e77fa3f6886fd72c314e4c01f2964c0fc56a5f imx-boot-imx93frdm-sd.bin-flash_singleboot
I also tested my own Yocto image for imx93frdm, which uses the same boot image hash.
I verified that SD boot selection works. In SD boot mode with no SD card inserted, there is no serial output. In SD boot mode with an SD card inserted, SPL starts and stops at “M33 prepare ok”. So the SD boot switch appears to be working.
I also verified that the official NXP .wic image contains the boot image at the expected 32 KiB / 0x8000 offset. Commands used:
WIC=nxp.wic
BOOT=imx-boot-imx93frdm-sd.bin-flash_singleboot
xxd -l 64 -s $((32*1024)) "$WIC"
xxd -l 64 -s 0 "$BOOT"
cmp -n "$(stat -c%s "$BOOT")" -i $((32*1024)):0 "$WIC" "$BOOT" && echo "NXP WIC contains boot image at 32K" || echo "NXP WIC does NOT contain boot image at 32K"
Result:
NXP WIC contains boot image at 32K
So the SD image appears to contain the boot container correctly.
To rule out only the 2024.04 SPL image being the issue, I built a newer boot image using Flexbuild/U-Boot. The SPL inside the built image shows:
U-Boot SPL 2025.04 (Apr 26 2026 - 16:21:54 +0000)
NXP FRDM-IMX93
I wrote this new flash.bin to the SD card at 32 KiB offset using:
sudo dd if=flash-imx93frdm-2025.bin of=/dev/sdX bs=1K seek=32 conv=fsync
sync
The board then printed the new SPL banner, confirming it was executing the new SD boot image:
U-Boot SPL 2025.04 (Apr 26 2026 - 16:21:54 +0000)
PMIC: PCA9451A
PMIC: Over Drive Voltage Mode
DDR: 3733MTS
DDR: 3733MTS
M33 prepare ok
However, it still stopped at the same point and did not continue to BL31/full U-Boot.
eMMC status:
Originally, the eMMC booted far enough to reach Linux login, but root login was broken because /bin/sh was missing in the root filesystem. During recovery attempts, the eMMC was rewritten from SD Linux using a .wic image. After that, eMMC boot also stops after “M33 prepare ok”. However, the same stop point occurs from SD boot using the official NXP image and also with the rebuilt 2025 SPL, so the current issue appears to be earlier than Linux/rootfs.
What I believe has been ruled out:
Wrong serial port: serial works and shows SPL output.
Bad PC power: tested with external 45 W wall adapter.
Wrong SD boot switch: SD boot mode with no SD card gives no output.
Missing boot image in SD image: verified boot image exists at 0x8000 / 32 KiB in the official NXP WIC.
Linux/rootfs issue: the failure happens before BL31/full U-Boot/Linux.
Host OS issue for UUU: UUU SDPS boot timeout occurs on both Linux and Windows.
Only the old 2024 SPL being bad: a rebuilt 2025.04 SPL also stops after “M33 prepare ok”.
Could you please help determine whether this is a known FRDM-i.MX93 early boot issue?
Are you using the BSP version we released?
Embedded Linux for i.MX Applications Processors | NXP Semiconductors
Which version BSP are you using and choose?
I will try to test on our board when I back from Labor holiday, I will back to office on Next Wednsday then will test, then give you reply my test result.
Wish you have a nice day
Best Regards
Rita
I'm using the LF_v6.6.36-2.1.0_images_FRDM_4.0_IMX93 image
I am back to office and will test on our board, then tell you the result.
Did you figure it out?
@Rita_Wang
Having the same issue...
I have never seen the BL31 to start booting with my imx-image-full-imx93frdm.rootfs-20260705225501.wic.zst scarthgap build.
Hi, I'm currently having the same issue. May I ask if you've figured out the solution yet?
Same issue here. Is there any update what's needed to allow the imx93 to boot from SD or alternatively let UUU work properly?
