One issue I'm always running into is the different pin out on boards for JTAG. So, the goal I'm trying to do is some allow a programming option to setup the pins different. So, now I don't need different break out boards.
Is this feasible? Good idea? I guess how do I get started? Yes, Yes, I'm a newbie...
The pinout can be changed in the buffer to whatever you want. It is just a few changes in the UCF file. Let me know if you need help, or have a custom request.
Ok.. I would like to take a look at it, something new to look at it. I thinking of some how do this on the fly...
on the fly might be possible in theory but not very simple .. often you have 3 or 4 general jtag pinouts so it might be simpler to just make 3-4 svf's and then upload the one you need...
Apropos on the fly reconfiguration of the BBv2 CPLD, robots noted in another recent message (viewtopic.php?f=51&t=2239&p=21368#p21368 (http://dangerousprototypes.com/forum/viewtopic.php?f=51&t=2239&p=21368#p21368)) that the CoolRunner II CPLD only guarantees 1000 write cycles. That should be plenty for most uses but it isn't a lot if you are doing a lot of on the fly changes. I hadn't realized that the number was that low until robots pointed it out.
Another approach is to have multiple pinouts in the same build that are changed by extra unused FT2232 pins (complicated because they are limited, only 16 between FPGA and CPLD). Better would probably be changing the pinout by jumpering or shorting one of the breakout pins.