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Topic: Missing RAM Pins (Read 4831 times) previous topic - next topic

Graynomad

True, if you use SMD connectors you have all the edge to work with as long as you're happy to have the board at the top of a stack.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

bheughan

I hate to bump a thread, but does the team have any comments on this? I do understand that mega compatibility > RAM/ethernet support, but for Arduino users who need the extra memory, is the only solution for the foreseeable future (6+ months) to either a) roll your own board or b) use the Atmel evaluation kit?

westfw

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is the only solution

I think so.  Officially, none of the Arduino platforms has ever supported add-on RAM (the add-on boards for the MEGA are all from third parties...)

Graynomad

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Officially, none of the Arduino platforms has ever supported add-on RAM (the add-on boards for the MEGA are all from third parties...)

At least it was possible with the Mega, the Due doesn't bring out one of the address lines (A6?) so you're screwed.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

grimepoch

So I've been looking into the SMC as well for an LCD and for what I can gather, since I don't use the ADDRESS pins for address, it seems I could still use the SMC to write to my LCD.  It's using 8-bits.  I do need ONE address line to tell it which memory internally to work with.  Although I am not 100% sure.  Still porting code from a Mega2560 project.

Graynomad

I think you'll be right there, the SMC has almost all the pins brought out for 8-bit access it's just that one address line so should be right.

If you do this let us know how it goes.

Of course one might wonder why you need to use the SMC for an LCD, LCDs are normally as slow as a wet week so memory-mapping one wouldn't help I think.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

UnaClocker

Looks like a good opportunity for a third party vendor to create a board using the Due's chip, but wired up for the hardcore extreme user. Rather than cloning the Due, it'd be an innovative evolution.
Brian from Tacoma, WA
Arduino evangelist - since Dec, 2010.

Graynomad

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Looks like a good opportunity for a third party vendor to create a board using the Due's chip, but wired up for the hardcore extreme user. Rather than cloning the Due, it'd be an innovative evolution.

I actually did just that when they first announced the Due, had the PCB laid out and everything. But I used the 3U because that's what they said they were using. Then they changed to a 3X and I didn't have the energy to re do it :)

I brought out ALL the signals (IIRC) with a form factor that allowed a lot of the board edge for user connectors and various modes that allowed addressing on the backplane etc. It also used the great power control ability the SAM has to shut down the board and save power. Plus it could control about 6A of external power.

Here's a render of the finished PCB



So yes, I think there is an opportunity for a bright young lad to make a "pro" version.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

Constantin

Rob, that is not only beautiful but impressive as it gets.

Graynomad

Thanks, it was pretty packed, 2.2" sq, 4 layers with almost as many components on the other side IIRC.

Shame to wast all that time, maybe I should re-jig it to use the 3X...I feel exhausted just thinking about it :)

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

UnaClocker

If you do re-do it, should toss in the ethernet jack while you're in there. How different is the pinout between the 3X and the 3U?
Brian from Tacoma, WA
Arduino evangelist - since Dec, 2010.

westfw

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should toss in the ethernet jack

A problem with this is that it's not just the ethernet jack.  You also need an ethernet PHY chip, which usually has its own crystal, and a relatively "serious" interconnect to the main CPU...

Graynomad

Yes I think Ethernet wouldn't fit, maybe I could squeeze in 1 or 2 more resistors :)

@UnaClocker
I remember it was enough to force a complete redo of the PCB, but I'll have another look.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

Graynomad

The 3U and 3X are totally different pinout wise so it's a complete redesign of both PCB and partial redesign of the schematic because the 3X has at least one extra feature (the DACs).

So unless there's some real interest (unlikely) that's all folks :)


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Rob
Rob Gray aka the GRAYnomad www.robgray.com

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