1176 MCU delay in pin control

[lfost]

I have an 1176 mcu.  I have pin R14 setup as an output, logic 0 at init, pull down enabled, assigned to GPIO9 gpio_io,00.  Instead of a low at power up, I see the pin go high for about 18 mS before it goes low.  I want to get rid of that 18 mS high.  This is in a bootloader so only a few lines of code being executed all of which have nothing to do with R14.  All other pins at power up act correctly meaning if init is low it is low at startup.   This is the only pin that is not acting correctly

I have tried the other GPIO assignments and all the other options for a GPIO output.  Nothing gets rid of that delay.    

[lfost]

Thanks Gavin for the reply.  I have already re-assigned the pin to all 3 gpio options.  Changing to a different pin assignment did not get rid of the delay.

[Gavin_Jia]

Hi @lfost ,

Thanks for your info. I tested on my side with RT1170-EVK, and got 9.9ms high after power up.

Also, I tested the case at the ResetISR() breakpoint and it also generates this high level. So suspect it is controlled by the boot phase, but need to wait for the internal team to reply as to the exact reason. Please give me some time. Thanks!

Best regards,
Gavin

[lfost]

Thanks Gavin for checking into this.  I will wait to see what you find out.

[Gavin_Jia]

Hi @lfost ,

I have been informed internally that this is a known issue, please check ERR050643.

https://www.nxp.com/docs/en/errata/IMXRT1170ACE.pdf

Thanks in advance!

Best regards,
Gavin

[Gavin_Jia]

Hi @lfost ,

Thanks for your interest in NXP MIMXRT series!

What if you multiplex R14 to GPIO3 gpio_io,00 and test again? My guess is that it might be due to the fact that GPIO7 ~ GPIO12 are in the LPSR power domain, i.e. connected to M4, and the M7 core accessing M4's GPIOs causes delays. 

Best regards,
Gavin