I love the
Avnet Zedboard; for learning a computing system from ground up, this medium priced board is the best thing I found so far; the flexibility to modify the HW forces me to really understand the low level concepts. The Zedboard has lots of I/O possibilities, but exposes ALL I/O pins available on Zynq (that's the CPU/FPGA package that runs the Zedboard) to the FMC connector. For serious dorking with Zedboard, a breakout board to access all those pins is necessary. For $150, Xilinx FMC105 board does exactly that. But when I mounted the FMC105 board on my Zedboard, I found that the JTAG stopped working, and discovered that it is because the FMC105 board also brings out the JTAG TDI/TDO pins, but leave them open--leading to a broken JTAG chain. Since I want to keep using the USB JTAG connector on the Zedboard, I had to short the TDI/TDO pins with a jumper, as you can see on the lower left corner of my setup, shown below:
Another handy thing to know: although it is hard to get at 3.3V on the Zedboard (as a protection measure, VADJ can only be either 1.8 V or 2.5 V--unless you solder on a jumper), there are a few 3.3 V on the FMC105. One of them is shown above, where I connected a red cable to my voltage regulator chip (not shown above). The JTAG pins above also has a 3.3 V source.
