Works just fine with dev board. Our board - different story. Is there a max external osc. that may be used if you plan on using jtag? Ours has 48 Mhz, connected only to XTAL1 in the described manner. The eval board uses 12 Mhz, which is the only real diff.
Using LPC2138 ...
Update. Got a known good program loaded via the serial port, so we now know that the running program is NOT setting the JTAG pins to be GPIO's. JTAG port still does not work.
With an 48Mhz Xtal there is a good chance to overclock the device. How is the PLL set up in the currently loaded application? Do you have an 10k pull-down on RTCK (P1.26)?
There is a new LPC2138 boot loader version which creates slightly different JTAG timing. The CARM V2.40 takes care of that. Do you have already this version? Reinhard
We changed the 48 Mhz out and matched the dev board with 12 Mhz - no difference in results.
I just set up the latest version, still doesn't work. We did some re-work on our board - lots of wires, and got past the comm failure message, so there is now some comm going on, but I don't think what we are sending is being received properly. Perhaps we need to re-lay out the board to get rid of noise... I will re-post a new thread when I know more.
Yes, 10K pull down on all signals as shown on the schematic that comes with the MCB2130 board.
A last tip: open Project - Options - Debug - ULINK Settings and reduce the Max JTAG Clock. Reinhard
I tried that yesterday - no dice.
I have figured out that the JTAG interface is disabled if pin P0.31 is pulled low after reset for LPC2138. This is not documented in Philips manual. This problem can easily be duplicated with MCB2130. If pin P0.31 is pulled low with 20Kohm resistor after reset, JTAG interface does not work.