Are the TRST and RTCK pins needed for JTAG on the LPC? I am
programming a Xilinx CPLD without these 2 pins fine on my prototype
board, but am having trouble getting the LPC to communicate with my
Keil wiggler.

Also, if these pins (P1.26-P1.31) are designated for a DEBUG port,
does that mean TRST and RTCK pins cannot be used for anything else (if
they are not needed for JTAG)?

Sutton Start a New Thread

Sutton Mehaffey wrote:
>
> Are the TRST and RTCK pins needed for JTAG on the LPC? I am
> programming a Xilinx CPLD without these 2 pins fine on my prototype
> board, but am having trouble getting the LPC to communicate with my
> Keil wiggler.
>

Depends on the JTAG unit and its config file. RTCK is "Return TCK", use
of this allows higher speed clocking of JTAG data. Is it needed? Not
really, but check to make sure your config file is not saying the use of
RTCK is enabled.

I believe that TRST is required.

For LPC2106, LPC2138 and LPC2214, I implement: TDO, TDI, TRST, TCK, TMS,
VCC, GND, and *RESET (main reset of board).
TomW

--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
---------------- Start a New Thread

That's interesting. Because on my Xilinx wiggler, the only lines on
the cable are TMS, TCK, TDO, TDI, VCC, GND. And, it has worked fine
for years. NO TRST or RTCK lines at all.

However on my LPC, I did find out that my TCK needed a pulldown
resistor instead of a pullup. That was the main problem. I
disconnected TRST and it still works fine. And, RTCK has to be low on
RESET for the LPC to be programmed, so I just have a jumper.

After programming, I can just redefine the pins to be GPIO and use
them for other things. I think that will work.

Sutton

--- In l..., Tom Walsh wrote:
>
> Sutton Mehaffey wrote:
> >
> > Are the TRST and RTCK pins needed for JTAG on the LPC? I am
> > programming a Xilinx CPLD without these 2 pins fine on my prototype
> > board, but am having trouble getting the LPC to communicate with my
> > Keil wiggler.
> > Depends on the JTAG unit and its config file. RTCK is "Return TCK",
use
> of this allows higher speed clocking of JTAG data. Is it needed? Not
> really, but check to make sure your config file is not saying the
use of
> RTCK is enabled.
>
> I believe that TRST is required.
>
> For LPC2106, LPC2138 and LPC2214, I implement: TDO, TDI, TRST, TCK,
TMS,
> VCC, GND, and *RESET (main reset of board).
> TomW
>
> --
> Tom Walsh - WN3L - Embedded Systems Consultant
> http://openhardware.net http://cyberiansoftware.com http://openzipit.org
> "Windows? No thanks, I have work to do..."
> ----------------
> Start a New Thread