Disable Few Selective IO expander pins in i.MX8MM EVK

[sreedhar_appala]

Hi,

I am working with i.MX8MM EVK and NXP Audio Board,

I would like to disable the EXP_IO0, EXP_IO1, EXP_IO2 pins.

I could not find any API to disable a particular pin. Could you please suggest any method, because we are facing some unwanted signals coming from Audio Board to i.MX8MM EVK via IO expander.

Thank you, Sreedhar

[sreedhar_appala]

Hi,

We have connected the NXP Audio Board MCIMX8M Audio Board to the i.MX8MM EVK (8MMINILPD4-CPU)

We have enabled the PCA953x interrupt GPIO1_IO12,

But Nand pins are always active, due to this, the interrupt line of IO expander is always getting triggered and causing the booting issue.

Could you please let us know how we can disable this.

Thank you, Sreedhar

[joanxie]

refer to the hardware user guide:

All digital I/O supplies listed in this table must be powered under normal conditions whether the associated I/O pins are in use or not, and associated I/O pins need to enable pull in pad control register to limit any floating gate current.

[sreedhar_appala]

Thank you Joanxie !!

I could find the comments from 

i MX8M Mini Hardware Developer's Guide  

3.9.1. i.MX 8M Mini unused input/output guidance

I need further clarification:

We have connected i.MX8MM EVK + i MX8M Audio Board (Part number MCIMX8M-AUD)

The pins of interest are EXP_IO0, EXP_IO1, EXP_IO2, EXP_IO3, EXP_IO4, EXP_IO5, EXP_IO6 and EXP_IO7, which are on the i.MX8MM EVK hardware are connecting to the CPLD in the Audio Board and they are active always. Which is not needed for us and causing system issues.

How to enable the pull in the software and discard/ disable these pins in software

Could you please share code snippet any.

Thank you, Sreedhar

[joanxie]

for control Exp gpios, you can see the dts file

"https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/fsl-imx8mm-e...

you also can refer to the link as below:

"https://community.nxp.com/t5/i-MX-Processors/How-to-enable-interrupts-of-EXP-GPIOs-from-PCA6416-in-I..."