8M Mini EVK JTAG

[andy_kiser]

Dear Yuri‌

Can you confirm that somebody tested the JTAG port on the i.MX8M Mini EVK? I'm asking because...

• I tried to hook up a Segger J-Link Pro to the EVK, but was not even able to scan the JTAG chain.
• If I connect the same JTAG cable to our own i.MX8M Mini hardware, JTAG chain scanning works as expected.

Background: We found that our own hardware (We call it "Verdin") is not fully compliant for Boundary scan, so I wanted to test it on the EVK).

Regards, Andy

[adevries]

Hi andy.kiser@toradex.com and YuriMuhin_ng,

I saw that you recently discussed this question and wanted to ask a question related to this. Did you notice the current consumption of the eval board dropping or rising significantly during your boundary scan testing? I'm trying to do some boundary scanning on my 8M Mini EVK and I've run into this problem. I will power up the eval board, and run a test that tells me if two pins I manually shorted are connected. The boundary scan will tell me they are connected (the correct answer) at which point the current reading on the power supply will drop from 120mA to 55mA. I will then run the same test again, and this time it will say the two pins are not connected (incorrect answer). At the completion of that test, the current will go back up from 55mA to 120mA. If I run the test a third time, the results are the same as the first test, with the current dropping back to 55mA. This cycle repeats forever. I am able to consistently reproduce this on the 8M Mini EVK, so I'm curious if this is a known issue with the processor, or if anyone else has encountered this problem.

Thanks,

Alex

[adevries]

Also, I have seen this same behavior on board I designed with the 8M Mini on it. In that case, the drop in current was due to VDD_ARM_0V9 and VDD_SOC_0V8 not drawing current anymore. The PMIC didn't report a fault, and the voltage levels seemed fine, but VDD_SOC_0V8 went from drawing 205mA to 10mA. VDD_ARM_0V9 went from drawing 80mA to 5mA. I'm betting the same thing is happening on the EVK.

[Yuri]

Hello,

 section 5 (Using BSDL for board-level testing) of Hardware Development Guide for the i.MX8Mm

definitely states about 8MMINILPD4 EVK  board:

"When using the BSDL file to force the i.MX8MM enter the boundary scan mode on the 8MMINILPD4 EVK:

..." 

https://www.nxp.com/docs/en/user-guide/IMX8MMHDG.pdf

Regards,

Yuri.

[andy_kiser]

Thank you for the link. It duplicates information which is also available in the reference manual

BTW: The link provided above seems to be broken. I used the following one, which requires a login

• i.MX 8M Mini Hardware Developer’s Guide

Regards, Andy

[andy_kiser · Accepted solution]

Dear Yuri‌

I was finally able to use JTAG BScan mode on the NXP i .MX 8M Mini LPDDR4 EVK Board (SCH-31407 REV C1), by setting all switches according to the i.MX 8M Mini Hardware Developer’s Guide:

• SW1101 [1-10] = 1111110001

and installing R106 to avoid power cycles every second.

I didn't analyze what was the difference compared to my first tests on this EVK.

Thank you for your support.

Andy

[andy_kiser]

Hi Yuri‌

That's too bad.  There's no special equipment required to test Boundary Scan. It can be done with any (cheap) JTAG adapter.

I see a strange behavior in boundary scan mode (see my other post), and would therefore really appreciate if anybody could share his experience with Boundary Scan on the i.MX8M Mini.

However, as you mentioned there is no experience on your side, we can close this ticket.

Thank you for your support.

Regards, Andy

[Yuri]

Hello, andy.kiser@toradex.com 

    If You really need Boundary Scan, but not software debugging, - please refer to the 

Hardware Development Guide for the i.MX8Mm, as mentioned in https://community.nxp.com/thread/521592 

< https://www.nxp.com/docs/en/user-guide/IMX8MMHDG.pdf >

Regards,

Yuri.

[andy_kiser]

Hi Yuri‌

I'm aware of this guide. But as stated before,

1.  We did a hardware design error on our own board, and it is impossible to patch it for being compliant with the guide. The results I see on my board make me doubt whether following the guide is sufficient to make boundary scan work.
2. Therefore I wanted to test Boundary Scan on NXP's EVK, but there it seems not to work at all. This was the reason to contact you here through the community.

Regards, Andy

[Yuri]

Hello, andy.kiser@toradex.com 

  Have You tried to pull up TEST_MODE?

Regards,

Yuri.

[Yuri]

Hello,

  i.MX8M Mini EVK JTAG was tested for software debugging.

I am not sure regarding Boundary Scan, since usually special equipment

is used for it; BSDL file is not used.

Have a great day,

Yuri

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