Bricked NXP CPUs

[Kerplunk007]

I have inadvertently bricked (I suspect) a couple of boards containing an NXP LPC2138 CPU. I access them by connecting a Segger JTAG directly to the JTAG pins on the chip, the PINSEL2 register controls whether the JTAG pins are configured for debug (JTAG) or for GPIO. Inadvertently, my code set this register to zero, which sets them to GPIO. Working through RAM this wasn’t a problem, because if I powered down the chip the loaded coded disappeared, and when the chip came back up the JTAG connection was there because default startup setting is JTAG. However, I made the mistake of burning my program to NVR, and it appears that as soon as the chip powers up the code takes over and disables JTAG connectivity. I’ve tried 2 means of connecting through JTAG, neither of them works.

The chip manual states that it is possible to force the mode to JTAG by pulling a particular chip I/O line low (P1.26). However, on this board that pin is not brought out in an accessible way.

I suspect the bricking is permanent, does anyone have any suggestions?

 

[danadak]

Can you not solder a jumper onto that chip pin and set it to the logic
level it needs to set JTAG mode ? Whats the chip package you are dealing with ?

Needle Probe for Electronic Testing

Needle Probe for Electronic Testing: Electronic components have shrunk and very small components are now closely spaced on printed circuit boards (PCBs). The close spacing makes electrical measurements with most probes difficult, with the probe tips being much larger then the pad…

www.instructables.com

Or lift the lead, if a TSOP type....


Regards, Dana.