GPIO voltage of USDHC1 bank

[tavinoth]

I configured sodimm pins 49,51,53 and 190 to GPO. I could measure high output as 1.8V. It suppose to be 3.3V.

It is reading 3.3V during boot up but later changing to 1.8V.

I have attached device tree for your reference.

[tavinoth]

imx6ull-colibri.dtsi (20.1 KB)
imx6ull-colibri-r1lc-p1lz.dtsi (7.3 KB)

[ToradexAI]

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Based on the context provided, it seems that the issue with the GPIO voltage dropping from 3.3V to 1.8V after boot is likely related to the device tree configuration or power management settings. Here are some steps you can take to address this issue:

1. Review Device Tree Settings: Double-check the device tree configuration to ensure that the GPIO pins (SODIMM pins 49, 51, 53, and 190) are set to maintain a 3.3V output throughout the operation. Look for any settings that might be altering the voltage after boot.

2. Check Configuration: Verify that the configuration for these pins is consistent and correctly set to output 3.3V. Ensure that there are no conflicting settings that might cause the voltage to drop.

3. Investigate Power Management Settings: Examine any power management features or settings that could be affecting the GPIO voltage levels after the system has initialized. These settings might be causing the voltage to change post-boot.

If these steps do not resolve the issue, further investigation into the specific device tree settings and power management configurations may be necessary.

Please, also check if these links can help you solve your problem:

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[sahil.tx]

Hi @tavinoth,
Which carrier board and image version you are using?

[tavinoth]

I will share the carrier board ver tomorrow.
I tested above in the Colibri eval board and custom board designed for my project needs. Both are behaving same way (as explained in the ticket).

I observed one more thing today.
GPO voltage is settling to 2.7V if I connect SODIMM_192 net (MMC_DATA0) to 3.3V.
GPO voltage is settling to 1.8V if I connect SODIMM_192 net (MMC_DATA0) to Open

Please note that USDHC1 (MMC SD1) is disabled since we configured it as ALT5 (GPIO).

[tavinoth]

Carrier board version details are given below.

[tavinoth]

The details are given below.

Platform info (from tdx-info)
Software (custom Yocto-based image):

• Bootloader : U-Boot

• Kernel version : 6.1.55-00020-g9dccaf40e612 #1 SMP Sat Sep 23 09:11:13 UTC 2023

• Distro version : VERSION_ID=6.4.0-devel-20240403095552-build.0
  Hardware (Colibri iMX6ULL on Colibri Evaluation Board):

• Toradex version : 0044 V1.1A

• Serial number : 14985046

• Processor arch : armv7l
  

[tavinoth]

I done some more testing.

The GPO voltage of sodimm pins 49,51,53 and 190 are varying linearly with respect to voltage at sodimm 192.

2.2V at sodimm 192 produced 1.8V at GPO.
2.3V at sodimm 192 produced 1.9V at GPO.
.
.
.
3.3V at sodimm 192 product 2.8V at GPO.

I am not sure why sodimm 192 is controlling the GPO voltage.