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Topic: Solution for the 5V vs 3.3V problem (Read 13 times) previous topic - next topic

Massimo Banzi

@Osgeld

Please provide your invaluable contribution when you have something more interesting to say.
If you don't like Arduino Due nobody is forcing you to be on this forum.

Saying "dumb" doesn't contribute to the discussion.

m


giantsfan3

@CrossRoads:
Looking good -- That layout image of yours is just to show the orientation and not the actual level translation itself, yes? Have you looked into the GTL2000... or the TXB0108 would work too, although I believe the GTL2000 is significantly cheaper.

derekmjenkins

Yes, it was just to get the headers defined, to show that 2 sets of headers could be made to fit next to each other - males down to the Due, and females up to shields.
I think I'll slide the 2nd set over some more to make room for signals to be buffered in the middle area  and then go back out, especially in the double row area.
Are there many mega shields? Maybe just drop that area and make sure the 20 Uno IO + power + ICSP headers are supported. Need to beef up the power traces.

Crossroads
(with the system calling me "derekmjenkins" for some reason - hopefully just a test towards solving my week day log in problems)

OsuDan

Hey guys,

I've been looking into something like this for a while as well. One thing that caught my eye was this pin converter shield for the UNO/Leo to go between the old pinout and 1.0

http://mayhewlabs.com/products/go-between-shield

Something like this could be implemented with logic converters between the connection points. This could also leads in some other interesting directions as well:

  • Being able to select/designate individual pins as 5v or 3.3v logic

  • Integrating dynamic pin assignment so the pinout could be adaptable to older shields configurations

  • And if you really wanted to get crazy, you could even wire the whole thing up to be driven by an integrated IC so you just add a library to your sketch and assign the pinout and voltage in software.

  • And since I've already gone way out in left field, to complete the prefect conversion shield, add either an IC to linearly scale the analog inputs or a separate 5v 12 or 16 bit ADC



EDIT: Just read the post about the GTL2000 and it got me thinking there has got to be a chip that could route pins and shift logic levels... Yup.

http://www.intersil.com/en/products/audiovideo/video-switching/unbuffered-crosspoint-switches/CD22M3494.html

Thoughts?

Graynomad

#9
Dec 12, 2012, 01:56 am Last Edit: Dec 12, 2012, 02:08 am by Graynomad Reason: 1
Quote
Being able to select/designate individual pins as 5v or 3.3v logic

Needs a lot of hardware, in banks of 4, 6, or 8 not so bad.

A crosspoint switch would be one way to go, you'd need a lot for them and last I looked they were not cheap. Also I don't think they level shift but at least they should pass the analog.

As for the analog you can get programmable gain chips or just make your own with opamps.

Either way you need more IO to control this lot, so add 1 or 2 I2C IO expander chips with jumpers to set the address so they don't clash with any shields.

In general I like the basic concept but it could very quickly turn into a cluster f*ck with 30 chips that cost 2x the Due and the shield you want to use.

Crossroads (aka derekmjenkins!?), you've obviously made a start, any thoughts on doing something?

Quote
Are there many mega shields?

I don't think so, I'd drop the extra stuff and just go for a standard shield.

EDIT: I just looked at the price for that CD22M3494 crosspoint switch, it's not too bad but still too much for this I think.

______
Rob

Rob Gray aka the GRAYnomad www.robgray.com

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