OK to use a filter cap on RESET when using JTAG?

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I'm designing an ATMega32A board, which is programmed and debugged via the JTAG interface.  The AVR042 app note recommends a .1 uF cap on reset unless you're using DebugWire or PDI.  The implication is it's OK to use the cap with JTAG.  Just wanted to confirm.  Thanks.

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Yes it's OK as the reset pin is not really used during debug, in fact some people leave it off the connectors.

 

However it comes into play when you disable JTAG via software, then you need it to get JTAG back.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Got it.  Thanks.  I'm not planning on fiddling with JTAG in s/w, but it doesn't sound like there's any harm in connecting reset to the connector, so I might as well.

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I'm not planning on fiddling with JTAG in s/w

But you may want to in order to use those 4 pins, I usually use them for things like status LEDs or switches.

 

But if you don't need those 4 pins then "anything goes". smiley

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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I don't need them for anything, and the only time I made them do double duty (in another project), I borked the CPU several times before I got the process right.  I'd just as soon avoid any chance of that by dedicating those pins to JTAG as long as I have the luxury of doing so.