IMX8M MINI ( pwm1.out pin is not going low, while shutting down )

siva17290 — Mon, 07 Feb 2022 13:47:31 GMT

Dear Nxp Team,

We have realized imx8mini custom board (MIMX8MM4CVTKZAA). we are running android 10 on this board.

We are facing the below issue:

We have interface the processor with display backlight driver(TPS61169DCKR).

To control this backlight we are using pwm1.out(GPIO5_IO05) pin. While shutting down the display we can see 1.54 volts on this pin(pwm1.out[AF8]).

We should get zero volts after shutting down the display, because of this backlight is still on.

When screen is lock/unlock & while controlling brightness pwm1.out pin works totally fine(we are able to see minimum(0v) to maximum(3.3v).

During test we have isolated pwm1.out(AF8) pin from the backlight driver, & found above observations.

Kindly let us know how to control this pwm1.out(AF8) during shutdown.

Re: IMX8M MINI ( pwm1.out pin is not going low, while shutting down )

art — Fri, 18 Feb 2022 10:09:26 GMT

The most likely cause of the issue is that, when the display is shutting down,
the AF8 pad becomes configured as GPIO input, that's why the voltage level on it
is floating. At that time, it is necessary to configure it as actively driven
GPIO output and set it to Low state.

topic IMX8M MINI ( pwm1.out pin is not going low, while shutting down ) in i.MX Processors

IMX8M MINI ( pwm1.out pin is not going low, while shutting down )

Re: IMX8M MINI ( pwm1.out pin is not going low, while shutting down )