I am trying to get the JB working with JTAG using jtag-0.5.1, as patched from the site.
I have a little bit of a non-standard JTAG cable (its a 244-based one - sort of like the Wiggler - but its made by Lattice Semiconductor). The pins are a bit different, so I modified the cable definition. I put some code in to test the individual bits (TCK, TMS, RESET, etc) to make sure that they are being set on the JB as the JTAG software thinks they're supposed to be - and all this appears to work - and at the right voltage-levels.
BUT, it obviously doesn't work!!
Is nRESET supposed to be (physically) high or low for JTAG programming?
When nRESET is asserted - what is supposed to happen to the JB? No matter if it as asserted or deasserted, the JB continues on playing its crappy into-videos. Shouldn't it "freeze" or something when its asserted - or in JTAG "mode"?
No matter *what* I do with JTAG - the JB continues on like nothing's there. I have verified I get proper signals/voltages on the JB pads. (BTW - I am doing this all on those test-point pads in the photo on the web site.)
I've also tried dropping the clock frequency too.
Any other tips anyone can give me?