State of GPIO immediately after GPIO power on

[thanhnhatle]

Hi all,

Our custom board is using i.mX7D and PMIC PF3000 as below:
i.MX7D : MCIMX7D7DVM10SD
PMIC : MC32PF3000A1EP

We found the below GPIOs drive level high immediately after its gpio power rail up, even when the gpio is pull-down by a 200-ohm resistor.
Exactly it is a 4ms high pulse. Please see the attach file for more detail.
Note that the power-on-reset is asserting, and the gpio are pull-down by a 1k resistor.

power-rail : NVCC_I2C
Pad: I2C3_SDA (ball K6)
I2C4_SCL (ball L1)

My questions are below:
1. Does the gpio drive high level during its group power up meet the i.MX7D specs ?

2. These GPIO are assumed as three-state during power up, is this right?

3. Unexpected high level output will conflict with the connected device. This phenomenon are seen on only 3 boards. On the other boards, these GPIO keep low during power up.
Do you have any idea in this case?

Best Regards

Nhat

[thanhnhatle]

Oops, reply wrong place.

I re-post below.

[jimmychan]

Which version of BSP are you using?

Do you check the iomux initial setting in the devicetree file?

Only 3 boards have this issue, please also double check the hardware connections and soldering on the board.

[thanhnhatle]

Hi Jimmychan

Thank you for your support.

This issue happen while the power-on-reset is asserting. Software does not run yet.
I think this is a hardware issue.

> Only 3 boards have this issue, please also double check the hardware connections
> and soldering on the board.

I have checked the hardware connection, but found nothing wrong.
I will check the soldering again by xray, and reheat it again.

Do you have any answer about my questions 1,2,3 above?

Best Regards
Nhat

[jimmychan]

I think you can refer to the page 147 in datasheet https://www.nxp.com.cn/docs/en/data-sheet/IMX7DCEC.pdf

The default function of these two pins are GPIO and 100K pull-down.