JTAG query

This is JTAG to debrick any JTAG device. Modem, cable boxes, dish boxes routers.
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ljkenny
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Joined: Sat Nov 24, 2007 1:17 am

JTAG query

Post by ljkenny »

I am trying to get in-circuit debugging working on a board I have. The trouble is; I only have the TDI, TDO, TMS and TCK pins on the board and I have a 14 pin USB JTAG. The software I'm using insists the board I'm running isn't running, when I know that it is.

Why would this be?
Can anyone help me get around this?
usbbdm
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Joined: Mon Jul 18, 2005 9:33 pm

Post by usbbdm »

TRST normally is not used but must be pull high if it exist. Otherwise the JTAG will not work. Nothing will come out from TDO.
ljkenny
Junior Member
Posts: 3
Joined: Sat Nov 24, 2007 1:17 am

Post by ljkenny »

I know what 'pulled high' means, but how do you do it with JTAG?

Can I just pump 3v's into it?
usbbdm
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Joined: Mon Jul 18, 2005 9:33 pm

Post by usbbdm »

Add 100ohm to 3V.
ljkenny
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Posts: 3
Joined: Sat Nov 24, 2007 1:17 am

Post by ljkenny »

Thank you, I'll give it a try!
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