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> Tv-out Hardware Hack For 5500?, Any available GPIO ports for hacking?
abdulhaq
post May 29 2005, 12:00 PM
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Hi

I've been wondering if there are any spare GPIO ports on the 5500 and if it's possible to get any of them out to the outside world.

One idea that occurs to me is to use the ports that control the IR transceiver. From reading various docs it seems to me that two GPIO pins go to the IR transceiver without any glue logic between them. Does this mean that I could cut them from the IR and solder some leads so as to get them out to the outside world?

I'd love to try and get the Zaurus to produce a TV signal a la

http://www.rickard.gunee.com/projects/video/sx/gamesys.php

I'd try the black and white first of course

I hope some of you can at least point me in the right direction.
Thanks
Abdulhaq
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QJimbo
post May 29 2005, 01:12 PM
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This would be extremely neat! I could load up the zaurus with videos, and play them back on a real TV biggrin.gif and it would be good for those executivy types who want to show a presentation easily. I think there are some Comapct Flash VGA output cards, but they can only update at one frame a second or something and require an old monitor that can cope with such low res signals.

Sorry I can't provide much technical info on the subject, but good luck ^^
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abdulhaq
post May 29 2005, 02:35 PM
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QUOTE(QJimbo @ May 29 2005, 10:12 PM)
This would be extremely neat! I could load up the zaurus with videos, and play them back on a real TV biggrin.gif and it would be good for those executivy types who want to show a presentation easily. I think there are some Comapct Flash VGA output cards, but they can only update at one frame a second or something and require an old monitor that can cope with such low res signals.

Sorry I can't provide much technical info on the subject, but good luck ^^
*


To be honest this would only be a neat hack, and not really much use for anything practical cool.gif

With two GPIO pins only 2 shades of gray could be achieved as well as black and the sync voltage. The speed of the processor would only allow a static B&W picture or perhaps at best a small and slowly moving animation.

Still I'd love to try it....

but I want to know if I have any chance of succeeding first.

Abdulhaq
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arniel
post May 31 2005, 06:33 AM
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Cool, so now my Z could emulate a ZX81 computer from 1981 :-D
The geek in me wants this so badly.
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craigtyson
post May 31 2005, 08:31 AM
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Even whit 2bits it should be possable to fool a TV into thinking you have more bits by using a small capacitor on the output to ramp the voltage change therfor allowing you to "half step" the voltage giving you virtual bits. It would need accurate timing on the changes of the output though
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abdulhaq
post Jun 1 2005, 01:33 AM
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QUOTE(craigtyson @ May 31 2005, 05:31 PM)
Even whit 2bits it should be possable to fool a TV into thinking you have more bits by using a small capacitor on the output to ramp the voltage change therfor allowing you to "half step" the voltage giving you virtual bits. It would need accurate timing on the changes of the output though
*


That's a great idea. Unfortunately more googling has left me with the suspicion that the GPIO pins can provide a maximum cycle rate of 500kHz - and TV needs tens of MHz:

http://lists.arm.linux.org.uk/pipermail/li...ary/002885.html

then again, perhaps I'm misinterpreting what is being said there.

I'm still curious if it is possible to get GPIO pins out of the Zaurus, and if pulling them off the IR transceiver is a possibility - does anyone know?

Abdulhaq
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omega
post Jun 1 2005, 03:44 AM
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I suggest you take a look at the numerous Microchip projects that connect to the tv, and use the serial port to communicate with the Z?
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abdulhaq
post Jun 2 2005, 12:03 AM
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QUOTE(omega @ Jun 1 2005, 12:44 PM)
I suggest you take a look at the numerous Microchip projects that connect to the tv, and use the serial port to communicate with the Z?
*


It was one of those projects that inspired me in the first place - but why buy an SX development board when I've got a Z sitting right in front of me - that's what I'm interested in.

Even if the GPIO is too slow for TV, a few GPIO ports on the outside of the Z could lead to some other interesting ideas.


Abdulhaq
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omega
post Jun 2 2005, 12:47 AM
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Fair enough. SX development board - why? I made my own programmer for my current project and you can get a free sample of a pic and start that way...
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abdulhaq
post Jun 5 2005, 02:37 PM
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QUOTE(omega @ Jun 2 2005, 09:47 AM)
Fair enough.  SX development board - why?  I made my own programmer for my current project and you can get a free sample of a pic and start that way...
*


well for B&W a PIC is fine - but if I did buy/wangle a microcontroller for a TV-out project then I'd rather have a crack at colour for which you need the MHz of the SX. Im no expert - this is just what I've read. What's your current project then?

abdulhaq
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