Date Modified

Here are some notes for connecting a Digilent XC2-XL CPLD board to a standard 20-pin JTAG header.

Note that Pin 1 for J1 is at the bottom of the board, closest to the J1 label (also has a square pad on the solder side).

In OpenOCD 0.8.0, the JTAG auto-detection misses the size of the XC2C256 Instruction Register (IR). It should be 8 bits, but autodetection sees it as 2, and then prints an error later.

# (20-pin) JTAG XC2-XL # (J1)
1 VREF VDD 6
2 VREF VDD 6
3 TRST_N NC
4 GND GND 5
5 TDI TDI 2
6 GND GND 5
7 TMS TMS 1
8 GND GND 5
9 TCK TCK 4
10 GND GND 5
11 RTCK NC
12 GND GND 5
13 TDO TDO 3
14 GND GND 5
15 SRST_N NC
16 GND GND 5
17 NC NC
18 GND GND 5
19 NC NC
20 GND GND 5