JTAG pin 7 question

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xtal_88
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Posted by xtal_88: Sun. Mar 23, 2014 - 01:48 PM
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Hi !

I have AVR JTAGICE mkII.

I would like to program ATmega128RFA1 on module deRFmega128-22M12.

In modules datasheet http://www.dresden-elektronik.de/funktechnik/products/radio-modules/oem-modules-derfmega/description/?L=1&eID=dam_frontend_push&docID=1250

or in picture pin 7 is tied to VCC.

I've been using JTAG with pin 7 unconnected(left floating).

So JTAGs pin 7 should be:

a) wired to VCC
b) left unconnected.

or it doesn't matter ?

Thank you !

Attachment(s): 

Image icon jtag.jpg

Tags:

AVR Microcontrollers, megaAVR and tinyAVR
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jpmargis
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Posted by jpmargis: Sun. Mar 23, 2014 - 02:38 PM
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Per the AVR JTAGICE mkII Quick Start Guide (which you must have read?), pin 7 is NC (no connection).

 

In consideration of others, please RTFM!

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xtal_88
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Posted by xtal_88: Sun. Mar 23, 2014 - 03:15 PM
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jpmargis wrote:
Per the AVR JTAGICE mkII Quick Start Guide (which you must have read?), pin 7 is NC (no connection).

Yep, got it:
http://www.atmel.com/images/doc2475.pdf

Quote:
Vsupply should be used if target board supplies power to the JTAG ICE

Quote:
Supply voltage to the adapter, this connector can be used to supply the adapter with power from a regulated power supply 3 - 5VDC (normally target VDD). This supply voltage input is automatically disconnected when a external power supply is connected.

So, it can be tied to VCC or left NC, doesn't matter.

I was looking at different schematic and some of them had that pin on VCC and some NC. I haven't paid too much attention to this up till now.

Thnx !

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jpmargis
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Posted by jpmargis: Sun. Mar 23, 2014 - 04:23 PM
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Here's a link to the correct document.

http://www.atmel.com/Images/doc2562.pdf

 

In consideration of others, please RTFM!

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Bronze Markdavid.prentice
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Posted by david.prentice: Sun. Mar 23, 2014 - 05:28 PM
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AFIK, the original Atmel JTAGICE-1 could supply power (5V) via pin7.
My JTAG-1 clone does not supply power.
I think that the $8 Chinese JTAG-1 clones might supply power.

All modern Atmel JTAG debuggers do NOT suppy power.

Quite honestly, it would only be useful for targets that run at 5V.
And fatal for those targets that don't.

David.

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