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Re: Carte Blanche JTAG cable questions



Charlie wrote:

I received my Digilent JTAG programming cable ($12 + shipping) today. I am to the understanding that it can be used to program the Carte Blanche card (slower than the more expensive cables). It has a PC parallel port connector on one end and a JTAG3 with SPI connector on the other.
The JTAG end is a single inline female for six pins labeled:

TMS
TDI
TDO
TCK
GND
VDD  1.8 to 5.5v

The Carte Blanche connector is male dual inline five pins in each row. Obviously not a match but the Carte Blanche card comes with a matching female ten pin connector with individual leads, each with a single female connector. I figure I can run wires between the female connectors on the one cable to the ones on the other if I can figure out which goes where.

Easiest thing to do is what Steve suggested: Break off a 6-pin length of pin header and use that to connect them. Basically a small strip of plastic with pins on 0.1" spacing sticking out on both sides.

The Carte Blanche cable connectors are labeled:

SOFT TMS
SOFT TDI
SOFT TDO
SOFT TCK
HARD TMS
HARD TDI
HARD TDO
HARD TCK
GND
CONNECT

Do I connect to the Digilent cable to the SOFT or the HARD pins or both?

Definitely not both. I believe it would be the HARD set, but don't take my word for it! I'd much like Alex or Steve to explain the distinction and uses of hard vs. soft JTAG.

Also the CB schematic shows the CONNECT pin as VREF (whatever that is). It also says "IF YOU ARE CONNECTING THIS INTERFACE TO USER BOARD A OR USER BOARD B DO NOT CONNECT THE REF PIN. REFER TO THE APPLELOGIC WEBSITE FOR DETAILS". Unfortunately, the Applelogic website seems to be down. So before I fry my CB card can anyone give me a heads-up on what to do?

That's definitely a Steve-or-Alex question...

Steve