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Multiple 1768, jtag chain

Topic last updated 05 Apr 2011, by Sty C. 2 replies
Sty C
04 Apr 2011

Hello,

I would like to design PCB with 3 LPC1768 chips on it. I would like to have only one jtag connector, therefore I should use JTAG chain.

Can you advise me the schematics I should use?

Ty

Matt Clement
04 Apr 2011

http://www.websters-online-dictionary.org/images/wiki/wikipedia/commons/thumb/c/c9/Jtag_chain.svg/654px-Jtag_chain.svg.png

OR

http://t3.gstatic.com/images?q=tbn:ANd9GcSAdK_zJE1eeRRMDAuOklsvJWGQt52ZlRsp8J7px74Ao74ABhnKyA

Sty C
05 Apr 2011

I connected them according to your schematics for a prototype.

In keil ide, I see all three of them, but they all have the same ID, and whichever I select to programm it only programms the last one in chain (device 3).

Do you know why is that ?

ps. I bought segger jtag programmator on ebay for about 35usd, so there is a big chance that it's not original, but it works normally with only one chip selected. I don't know could that be the reason...