OpenWrt Forum Archive

Topic: JTAG Help

The content of this topic has been archived on 23 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.

Post #1
samurai123
14 May 2013, 00:55

Hello Guys,

I'm looking for some help to get this JTAG working. I think the JTAG is not wired properly maybe to make it inactive on purpose.

This is what I see connected to the JTAG pins (20 in total) which I think follows the standard ARM-20 pinout.

Vref, Vcc @ 3v
4.7K pull up resistors - nTRST, TDI, TMS, TCK, DBGACK
No pull up/down resistors - TDO, nRST
4.7K pull down resistor - RTCK, DBGRQ
All GND pins are properly connected to GND.

I think TDO and nRST needs to be pulled up with probably 4.7K to make it work. Am I right or is there anything else needs to be looked at?

Thanks

Post #2
samurai123
25 May 2013, 00:39

Can someone recommend a good logic analyzer with JTAG protocol support?

Thanks

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