JTAG device scan problems

[lpcware]

Content originally posted in LPCWare by Flo on Mon Mar 31 04:37:52 MST 2014
Hi there,

I am using a LPC4357 (Embedded Artists OEM Module) with Red Suite 5 and the Red Probe+. Recently I can't use the JTAG interface for debugging anymore (it was always used for debugging the Cortex M0).
It looks like the Debug Probe is not able to scan/find the devices correctly. There appears a list with 7 entries and the Cortex M0 entry is splitted up (as you can see in the attached image).

I still can programm both cores and also debugging the Cortex M4 using the SWD-Interface still works. The applications also execute regulary. I already created new debug configurations reloaded/reset the firmware to see if the issue lies there but nothing helped. The module is in use for almost one year now, so I don't think it is a configuration problem. May the MCU be damaged?

Best regards,
Flo

[lpcware]

Content originally posted in LPCWare by Flo on Thu Apr 03 06:39:35 MST 2014
I  just organized a LPC-Link and checked the JTAG chain on the OEM board. The LPC-Link also finds the "incorrect" device list. I also tested the Red Probe+ on another target. It works fine.
So I'll buy a new OEM Board, Or is there a way to fix it?

Regards,
Flo

[lpcware]

Content originally posted in LPCWare by lpcxpresso-support on Tue Apr 01 21:35:38 MST 2014
This sounds inconclusive. The VIL for 3V3 CMOS logic is 0.8V, so 0.7V is technically below the threshold.

Can your Red Probe+ successfully interrogate the JTAG scan chain on any other target? If not, it might pay to remove the cover screws on the Red Probe+ and double check the cable connections.

Regards,

LPCXpresso-Support

[lpcware]

Content originally posted in LPCWare by Flo on Tue Apr 01 05:21:15 MST 2014
Actually not, but I used a scope to take a look at the signals. It shows that the TDI line is not always on 0V or 3.3V (This is what i would expect due to the pullups/-downs).
Unfortunetly the line is at ~0.7V sometimes. I attached a sample screenshot with CLK and TDI. Is there a consequence that can be drawn out of this behaviour (damaged MCU or Debug Probe)?

[lpcware]

Content originally posted in LPCWare by lpcxpresso-support on Mon Mar 31 23:57:42 MST 2014
Can you try a different debug probe? Another Red Probe+, or a LPC-Link or LPC-Link2?

[lpcware]

Content originally posted in LPCWare by Flo on Mon Mar 31 07:02:58 MST 2014
- Nothing has been added to the JTAG chain
- I tried the scan without my JTAG adapter cable adapter (so I used the original connector of the Red Probe+ on the EA LPC4357 DevKit). The scan result is the same as before this way.
- Recreation of debug configuration: Doesn't help.
- I booted the MCU in ISP mode and started JTAG: Same result as before.

[lpcware]

Content originally posted in LPCWare by lpcxpresso-support on Mon Mar 31 05:55:24 MST 2014
A few suggestions/things to try
- has anything been added to the JTAG scan chain? Perhaps for boundary scan or test purposes
- have you tried changing the (JTAG) cable?
- try deleting and recreating the debug configuration
- try booting the device in ISP mode

Let us know of your results