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burn

Beginner

Date of registration: Oct 27th 2017

Posts: 2

1

Thursday, November 16th 2017, 7:28pm

J-Link error - "Could not measure total IR len. TDO is constant high." SWD stuck in reset

I am trying to use J-Link to debug my custom board with arm microcontroller - LPC2148FBD64-S.
I am using SEGGER J-Link Commander V6.20h with Firmware: J-Link Pro V4.
S/N : 174403384




When trying to use the JTAG debugger I get the error - Could not measure total IR len. TDO is constant high.
I do read Vtref close to 3.3V as expected.
So, when I couldn't get the JTAG to communicate with the board, I tried SWD and this time Jlink driver tries to download the application on the board, but it just gets stuck in the reset handler and I just see the debugger stopping at the reset vector line of code in my cstartup file.
Also find attached the debug log when I used the SWD.

SWD.txt


Do you have any suggestions for a fix or what the problem might be?

Thanks.

This post has been edited 1 times, last edit by "burn" (Nov 16th 2017, 7:29pm)


SEGGER - Nino

Super Moderator

Date of registration: Jan 2nd 2017

Posts: 430

2

Friday, November 17th 2017, 8:56am

Hello,

Thank you for your inquiry.

The described behaviour is rather odd.
Was the J-Link working on another target?
Do you have an eval board with the particular chip to test against?
Could you please post the full Commander output when trying to connect?
How is JTAG/SWD wired on your custom board?

Best regards,
Nino

burn

Beginner

Date of registration: Oct 27th 2017

Posts: 2

3

Tuesday, November 21st 2017, 5:56pm

Hi Nino,

The Jlink has been working for another board that I used for other applications. It had the same microcontroller LPC2148.
I have 8 pin JTAG connection available on the board. So I just use the 3.3V, nTrst, TDI, TMS, TCK, TDO and GND pins from the 20 pin JTAG.
Find below the debug outputs









Thanks!

SEGGER - Nino

Super Moderator

Date of registration: Jan 2nd 2017

Posts: 430

4

Wednesday, November 22nd 2017, 9:21am

Hello,

The error output you are seeing suggest that the JTAG connection is physically not connected properly.
At least TDO is not wired as expected and is pulled constantly high.
Please check your physical debug connection again and if all for JTAG needed connections are present.

Best regards,
Nino