IMX8m-plus ECSPI2 MISO problem

[Tolmachov]

Spoiler

Hello,

We use SOM IMX8m-plus form Compulab. An external spi module is connected to this SOM via ECSPI2 interface. This module is the only one connected to this ECSPI2, there are no other devices. When I connect the oscilloscope to the spi lines, the CS, MOSI and SCK lines behave correctly. But there is a problem with the MISO line.

When it is disconnected from the SOM imx8, the correct data from the external module is visible on the oscilloscope.



But if I connect MISO line to SOM imx8, the data changes.



We checked the external spi module and hardware, everything works well.

We assume that the problem is in the IMX8 ECSPI settings.

Are there any additional settings in the device tree or the kernel driver for ECSPI?

I will be very grateful if you can send an example of how to properly set up a MISO line.

Thank you.

[JosephAtNXP]

Hi,

Thank you for your interest in NXP Semiconductor products,

Are the settings for speed equal in both sides?

Have you tried with other modules maybe from other vendors?

I would strongly recommend to try to reproduce within two boards and if this is not possible, UART3P3 has a pinmux ability for ECSPI1.

Regards

[Tolmachov]

Thank you very much for your answer.

Yes, master and slave work at the same speed.

We also tried connecting this external module to the Raspberry Pi, it works.

We observe such strange behavior of miso only on SOM IMX8m-plus.

Perhaps there are some specific settings for the miso pin or spi controller?

We have also already seen a similar problem on this forum without an answer. https://community.nxp.com/t5/i-MX-Processors/IMX8QM-SPI-MISO-line-not-working/td-p/1441266