Hi, > The buffer you use is unidirectional, and one of the signals (TDI or TDO, > check with the JTAG spec and the Spartan 6 documentation) goes in the > opposite > direction (device to JTAG cable). > > You should put the buffer in the opposite direction for this signal. When > powered with 3.3V, the buffer can probably recognize the 2.5V from JTAG as a > high level (see p.4 of the buffer datasheet).
I checked the datasheet, Page 15 of DS_FT2232H.pdf, pin 18 FT2232H is TDO, channel A's JTAG serial data input. Pin 16/17/19 are output pins. Page 16 of ds300.pdf, pin 8 TDO of JTAG connector is test data out from target devices. http://www.xilinx.com/support/documentation/data_sheets/ds300.pdf Since 2.5V is above the threshold of the FTDI, I just remove that buffer. Please check the mail of reva04. Regards, Yanjun Luo. _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkym...@freenode Webchat: www.milkymist.org/irc.html Wiki: www.milkymist.org/wiki
