About i.MX8M Mini 's GPIO1_IO04 usage

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About i.MX8M Mini 's GPIO1_IO04 usage

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937556508
Contributor I

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
>;
};
};
};

gpio4.PNG

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2 Replies

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igorpadykov
NXP TechSupport
NXP TechSupport

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

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124 Views
937556508
Contributor I

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

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