imx6 Power-on GPIO states

[kimyoung]

I am trying to control a GPIO2_IO10(gpio42) in imx6 on order to control a Laser power,

I can take control on the gpio42 via U-boot and device tree, but the problem is the gpio state after power on.

According to the document, the initial state of gpio42 is input with 100k pull up,

but ihave to always keep the gpio42 low to prevent an unexpected Laser on state.

Anyone will shed light on how to keep gpio42 low after power on, even though it is initailly  set as a pull up input state?

Appreciated in advance.

[CarlosCasillas]

Hi kim,

You could modify pin parameters on U-boot, but then you also need to ensure of the pin assignments (Device Tree config) when the OS boots up, as it will override U-boot configuration.

Anyway, in order to ensure a specific level on a pin when the processor powers up, it is recommended adding external pull up/down resistors.

Hope this will be useful for you.
Best regards!
/Carlos
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