No U-Boot on iMX8MM and iMX8MP at higher temperatures

[jaskis]

Hi NXP Team

We have designed a SoM using the iMX8MM. To validate our Products, we test the SoMs in a climate chamber where we put the SoM in the temperature conditions specified for the given Product.

During these tests, we have seen that in some rare cases there is no U-Boot output at the higher temperature. We measured the supply voltage of the SoC and the RTC clock which are necessary. They all work fine. It is also strange, that sometimes at the higher temperatures the SoC will boot and sometimes not.

Have you seen such behavior in your validation? Is there anything blocking the boot sequence of iMX8MM in Hardware/Bootrom at higher temperatures? Is it possible to turn on the debugging on Bootroom/ScuFirmware to get more information, what is happening when there is no U-Boot shown?

Best regards,
Jaskaran

[jaskis · Accepted solution]

This issue is solved. The root cause was the Reset signal of SoC not being released at higher temperatures due to leakage. The correction was made in Hardware.  

[jaskis]

HI @Rita_Wang 

Thanks for your reply. All other chips are working fine. We are trying to check why the SoC is not working properly.

[Rita_Wang]

It will depend on the other chips work temperatures, make sure all the chips you are using can work well at some high temperatures.