i.MX8M U-Boot UART1 problems

pavelr — Thu, 30 Dec 2021 14:41:26 GMT

Sorry for taking your time, but i'm lost. I'm new to both iMX and U-Boot, therefore a mistake might be visible to professionals like you.

We have built a system closely resembling i.MX8M-evk board, which we have trouble properly booting up. To boot it up we have started with cloning a U-Boot official git repository. In order to build a binary we have followed https://u-boot.readthedocs.io/en/latest/board/freescale/imx8mm_evk.html example with gcc-aarch64 compiler and several device tree changes: instead of uart2 we are using uart1 (unsuccessfully) and several other i2c changes. The image was prepared to be used within a board-internal flash memory or an emmc.
! Except the very last step:

# dd if=flash.bin of=/dev/sd[x] bs=1024 seek=33 conv=notrunc

The first build had a misconfigured i2c device (several devices took same address: pmic and port expander), which did not boot up a pmic properly. Second build actually corrected that mistake and we were able to boot up and use "UUU"-tility to play around with a binary. I'm guessing that mcu clocks and an I2C have booted up properly. But there were no signals on either uart lines (we have changed "used" console device to uart1), so no U-Boot startup message was shown.

Then we have added the above mentioned line to a build process (i had doubts about it since the beginning), and a new upload through uuu-tility rendered the device useless. We only had 2 boards, so no way to check a new firmware now, until we manufacture an another batch. We had no jtag capabilities before and uuu does not recognize a device from now on. I understand that the above mentioned line was aimed at an external sd card. A blank space of 33 kilobytes? why not 32? We also had to add 0x55AA sequence in order for the rufus to recognize the image.

Another question is: the above mentioned line lists 33 kB length blank space, but several binaries (like from a similar verdin board, presented in a u-boot repository) have a different blank space at the beginning - 3.3kB. Please point me in the right direction: am i using an outdated tutorial or are there other factors at play?

Re: i.MX8M U-Boot UART1 problems

igorpadykov — Thu, 30 Dec 2021 23:39:52 GMT

Hi Pavel

what processor used in the case, i.MX8MQ or i.MX8M Mini (these are different).

Recommended to use uboot from nxp source.codeaurora.org/external/imx/ repository:

https://source.codeaurora.org/external/imx/uboot-imx/tree/board/freescale/imx8mq_evk?h=lf_v2021.04

https://source.codeaurora.org/external/imx/uboot-imx/tree/board/freescale/imx8mm_evk?h=lf_v2021.04

and use attached documents.

Best regards
igor

topic Re: i.MX8M U-Boot UART1 problems in i.MX Processors

i.MX8M U-Boot UART1 problems

Re: i.MX8M U-Boot UART1 problems