IMX8m Plus Boundary Scan Issue

[Talal]

I'm building a custom board using IMX8m Plus, and I want to use boundary scan to test the connections of the board. In order to do so, I am experimenting on the (8MPLUSLPD4-EVK) to check the JTAG connections and what need to be done to enter Boundary Scan Mode. I removed R32 (JTAG_MOD connection to GND) and soldered R313 2.2KOhm (JTAG_MOD to VDD_1V8). In addition, in SW4 I changed all the BOOT_MODE status to High, and I Measured the Voltage of POR and it is high. When I tried to check the chain to start the test, the Power LED (D25) turns off and when I disconnect XJLINK it goes back ON. The message I got from XJLINK2:

Starting Check Chain ...

No valid data returned from the JTAG chain.

perhaps the pin map is incorrect, or the board is not powered.

Check chain failed

Any idea what seems to be the problem?

[riteshmpatel · Accepted solution]

Hi @Talal,

Hope you are doing well.

Please accept my apologies for delay in response.

One can refer Example 3: No Valid Data Returned from the below link to know the possible causes of the error:

https://www.xjtag.com/support/application-notes/jtag-chain-debugging/

In addition to the above, could you please also check what is the status of JTAG reset pin?

Thanks & Regards,

Ritesh M Patel

[Talal]

Thank you so much for your help Ritesh, the issue was with the test reset sequence, nRST was low and the PMIC reset pin is active low. I just changed the nRST state to high and it worked fine!

Thank you.