hello all,
I wish to know more about jtag speed parameter in openocd cnfg file. As per documentation 1/6th of processor freq has to be used as jtag freq.
What should be the speed argument if i m using the ocd with fast (pll enabled) targets like arm9 with general bitabang based wiggler interface. I am gettng the IR mismatch n scan chain errors…can anybody plz tell me in detail about it?
thanks!
best regards,
rk
For most of the currently supported JTAG interfaces this setting is a divisor - the maximum speed supported by the device is divided by (1+jtag_speed). In the case of a Wiggler the maximum frequency heavily depends on your host PC, but usually is something around 200-300kHz, i.e. it should be slow enough not to cause any problems.
With wigglers all kind of things can go wrong - some have a non-standard layout of the reset lines, others have general signal integrity issues. The OpenOCD is known to work for example using Olimex’ ARM-JTAG.
Regards,
Dominic