JTAG Interface Not Working After LPC-Link Board Separated

lpcware · ‎06-15-2016

Content originally posted in LPCWare by Ulysses on Wed Jan 20 06:40:01 MST 2010
I have a customer who is trying to connect the LPC Link to a prototype carrying the LPC1313 using the JTAG interface and it is not working. They are using LPCXpresso 3.1.2 and get an error message when starting a debug session.
They see no signal when they put an oscilloscope probe on the JTAG clock signal (TCLK). It was working with the LPC1343 development section of the board before cutting the traces on connector J4. Since communications with this section is thru the SW interface, how does the LPC-Link knows when to switch from the S/W interface to the JTAG interface? Is it by hardware (where the signal has to be in a particular state) or software (a location in LPCXpresso where you can select between the two interfaces)? Do we have a document describing how to connect to a custom target board while using LPCXpresso? They have verified that the connections between the LPC-Link J5 connector and the target LPC 1313 are as per Figure 33 of the "LPCXpresso Getting Started" document are correct.

lpcware · ‎06-15-2016

Content originally posted in LPCWare by NXP_Europe on Wed Jan 20 08:15:48 MST 2010
Hi Ulysses,
The LPC1300 doesn't have JTAG available of debugging, only SWD. The JTAG pins mentioned are for testing purpose only. So if you select a LPC1300 device in the project settings it will always use the SWD. So make sure the SWD pins are connected.
I tested the LPC-Link with a different target board and works without a problem.

Please help us a bit more and place the exact error message.

lpcware · ‎06-15-2016

Content originally posted in LPCWare by CodeRedSupport on Wed Jan 20 07:38:18 MST 2010
Hi,

You don't say what error message the customer is receiving - that would really help.

Also, I didn't think that LPC13 family had a JTAG *debug* interface - it uses SWD only. I think it has JTAG for boundary scan and nothing else. In other words, the customer has to use the SWD interface for debug, not JTAG.