About i.MX8M Mini 's GPIO1_IO04 usage

[937556508]

Hi,

I have trouble using GPIO1_IO04 of MIMX8MM5DVTLZAA, and it cannot be pulled high.

On the schematic diagram, I connected it to a push switch and pulled it up to 1.8V externally. When there is no power on, I measured the impedance of GPIO1_IO04 to ground as 4.02K ohms. After powering on the CPU, I measured the voltage of GPIO1_IO04 as 0V.
The attachment is part of the code and schematic diagram.

Looking forward to your help.

Best regards!

/delete-node/ &pinctrl_usdhc2;
/delete-node/ &pinctrl_usdhc2_gpio;
/delete-node/ &pinctrl_usdhc2_100mhz;
/delete-node/ &pinctrl_usdhc2_200mhz;

keys {
compatible = "gpio-keys";

key-rtn {
label = "key_return";
gpios = <&gpio1 4 GPIO_ACTIVE_LOW>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpio_return>;
linux,input-type = <1>;
linux,code = <KEY_F12>;
debounce-interval = <15>;
};
};

&iomuxc {
imx8mm-evk {
pinctrl_gpio_return: gpiortngrp {
fsl,pins = <
MX8MM_IOMUXC_GPIO1_IO04_GPIO1_IO4 0x19
>;
};
};
};

[igorpadykov]

Hi 937556508

reason may be that it is shorted to some other signal, one can try to test

it by toggling, attach jtag debugger or with memtool:

https://source.codeaurora.org/external/imx/imx-test/tree/test/memtool?h=imx_5.4.47_2.2.0

use IOMUX Chapter of i.MX 8M Mini Applications Processor Reference Manual

Best regards
igor

[937556508]

Hi igor

I rechecked the code and blocked all lines of code about GPIO4.

At the moment the board is powered on, the oscilloscope captures a high level on GPIO4, and then pulls it down immediately.

I tried to use the following Linux command to change the state of GPIO4, but nothing changed, the state of GPIO4 was always low.

echo 4 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio4/direction
echo 1 > /sys/class/gpio/gpio4/value

But when I used the same command to set GPIO12, I got the desired result. GPIO12 is high.

echo 12 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio12/direction
echo 1 > /sys/class/gpio/gpio12/value

I want to confirm whether GPIO4 has special use on the development board.

Let me emphasize that the boot file I currently use is based on the 8MMINILPD4-EVK development board. In addition, I have not made any changes to the configuration of PMIC-BD71847AMWV.
The development board uses GPIO4 to configure the MUXSW_VOUT output of the PMIC.
But my investigation did not yield any results.

I need your help now.

Thanks in advance