lpc1817 jtag disabled

[josvisser]

I have a few boards with an LPC1817 on which the JTAG is no longer working.

I have checked all the conditions that may disable the JTAG.

- Pin 28 DBGEN is not connected and pulled up internally

- OTP bank 3 is not progammed

- The CRP is not active

- CREG5 is not loaded

Can anybody give me a hint why the JTAG stops working.

I have connected both LPC-Link2 and J-LinkPro without success.

I can only program through ISP.

Regards,

Jos

[bernhardfink]

Hi Jos,

sometimes SWD ist still working when JTAG is not.So make a crosscheck.

Reason could be a damage of one of the JTAG inputs. See this thread for more details:

https://community.nxp.com/thread/487475 

Regards,

Bernhard.

[josvisser]

Thanks Bernhard,

We will have a closer look at the connection sequence and grounding of power and jtag at our production facility.

Regards,

Jos