IMX8ULP Boundary Scan EXTEST issues

[Corebb]

I have an IMX8ULP chip, and I want to use JTAG for Boundary Scan.

I can successfully connect and run in SAMPLE mode, and I can see the IO status. However, when I switch to EXTEST mode, the connection immediately drops, and it seems like the chip powers off and resets right away.

I saw documentation related to the IMX8M PLUS that mentions the need to set PMIC_STBY_REQ to low, and several BOOT_MODE pins need to be configured to different states.

But in the IMX8ULP, this part is omitted, and I couldn't find any reference in the documentation about whether the BOOT_MODE needs to be set to a specific state. I also don't know how to set PMIC_STBY_REQ to low.

My request is to enter EXTEST mode in Boundary Scan on the IMX8ULP(MIMX8UD7CVP08SC） and control the IO levels. I need help to check if any specific pins need to be configured in a certain state to achieve this. If so, how should this be done? Thank you.

[Corebb]

Need Help.

[Bio_TICFSL]

Hello,

JTAG is different from MX8MPlus then

JTAG_TDO -> JTAG_TDI

JTAG_TDI -> JTAG_TCK

JTAG_TCK -> JTAG_TDO

JTAG should work with these changes.

Regards

[Corebb]

Do you mean i need to change the JTAG connection from TDO to TDI, TDI to TCK, TCK to TDO?

Why is that?
Originally, i can connect, and get the IDCode succeesfully without change the connection.

After change it just like you said, it even can't connect.


The only problem I originally have, is it can't enter the EXTEST mode, it just like the chip reset when i send EXTEST command.