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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9491

Posted: 03:48pm 10 Aug 2014

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Hi folks.

Do I NEED to use this line on the CMM circuit?
QFP pin 74, C14 - connects to pin 9 on the VGA socket.

It's just going to be a bit hard to get to this pin on my custom layout, so wondering if I can leave it off?

I am never going to want composite video out on this unit - it will be permanately VGA, if that helps at all.

Thanks for any replies.

EDIT: Most of the images I can find on the net for the VGA pinout, say that pin9 is not used, but a couple of images I found say that it is +5v. One image even shows pin 9 being connected to ground.Edited by Grogster 2014-08-12

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TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6220

Posted: 05:12pm 10 Aug 2014

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You should be able to leave it floating. That's how it appears with no monitor plugged in or a minitor which ignores pin 9.

Change log for MMBasic Ver 4.0A
Colour Maximite only: To avoid compatibility issues with some VGA monitors that use pin
9 on the VGA connector for other purposes, versions 4.0A and later will default to having
the composite video feature turned off. To enable composite video connect to the Colour
Maximite via USB and issue either one of the following two commands:
CONFIG COMPOSITE PAL -or- CONFIG COMPOSITE NTSC.
Either of these two commands will enable the composite detect (pin 9 on the VGA
connector) and select the correct video timing. The command only needs to be run once and
will be remembered even with the power turned off.

Jim

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bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2946

Posted: 05:13pm 10 Aug 2014

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Groggy,

I am fairly certain that pin9 is used as a VGA sense line on the CMM. If it is GND it will be VGA if left floating it will be Composite.. it works on the basis that many VGA monitors have this line GNDed. If you are worried take it to either a 2 pin header or small solder shorts GND one side the PIC line the other.

Mick

PS. I think this can be overridden by an OPTION command... It has been a long time since I powered my CMM up I am afraid to admit.. uMites have taken over for me.

Mick

EDIT***

Mind you you can get a thin trace through to pin 9 but it may fail your track rules... just ignore the error.. I think I used 0.060" pads which means you can still squeeze a thin 6-8mil track in for the small distance it needs to be.

M

EDIT 2 ****

I just checked... I used 0.070" dia pads with 0.047" holes which leaves a 0.032" clearance (you need to use several small lines at non 90degree angles to get it through) between pad rows.

It is possible to get an 8mil (0.008") track with 8mil clearance but it isnt easy.

Mick
Edited by bigmik 2014-08-12

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9491

Posted: 05:37pm 10 Aug 2014

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Thanks very much, guys.

Smoke makes things work. When the smoke gets out, it stops!

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