New: Arduino Mega SRAM expansion shield kit

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Chuckt
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New: Arduino Mega SRAM expansion shield kit

Post by Chuckt » Tue May 07, 2013 1:48 pm

New: Arduino Mega SRAM expansion shield kit
The Ardiuno Mega boards come with only 8 kB SRAM, which seems enough until it ain't! This Arduino Mega SRAM expansion shield PCB is based on the design by Andy Brown - andybrown.me.uk - to provide an additional 444 kB of SRAM. This extra memory can be used interchangeably with the 8 kB of in-built chip SRAM.
http://www.lagrangianpoint.net/blogs/co ... shield-kit

The schematics are here:

http://andybrown.me.uk/wk/2011/08/28/51 ... ga-design/

Commentary on the SRAM expansion shield kit:

http://andybrown.me.uk/wk/2013/05/05/51 ... ld-format/

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brad
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Re: New: Arduino Mega SRAM expansion shield kit

Post by brad » Tue May 07, 2013 10:10 pm

I'd like to see the kinds of projects people are making that would cause them to need anywhere near 8KB of SRAM!

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Re: New: Arduino Mega SRAM expansion shield kit

Post by Chuckt » Tue May 07, 2013 10:42 pm

I think graphics and LCDs would use a chunk of memory. I'm guessing a robot or a process like a CNC machine might take up some space.

The reason I like these guys is because their tech would help me build a SBC.

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Re: New: Arduino Mega SRAM expansion shield kit

Post by brad » Wed May 08, 2013 7:48 pm

Actually you're right. Some graphics LCD screens would certainly need quite a large buffer. I'm not sure exactly about CNC machines but I guess if you loaded up the microcontroller with large amounts of data at a time you would certainly need a lot of SRAM for that. What is an SBC? single board computer?

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Re: New: Arduino Mega SRAM expansion shield kit

Post by Chuckt » Wed May 08, 2013 10:24 pm

Yes, I meant "Single Board Computer".

I also thought that it could be used as an E-reader or in conjunction with a computer with all of that memory even. I'm also wondering if the memory is fast enough to keep up with an 84 MHZ Arduino Duo.

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Re: New: Arduino Mega SRAM expansion shield kit

Post by bit.cyber » Fri May 10, 2013 1:06 am

It's a good question - why does one need so much SRAM. I decided to create the SRAM expansion shield, based on Andy Brown's design, because of a GPS Disciplined Project I'm working on. (You can see some of the results at http://www.aethersdr.org.)

The two core reasons are:
1. The messages from the Jupiter TU60-D120 GPS receiver that I'm using can be quite long, i.e., 264 16-bit words
2. I prefer to program in C++.

The messages from the GPS receiver are certainly not all 528 bytes long, although many are long enough. It's just that one needs to have enough memory available in case one of these is to be processed. And dynamically allocated memory is not ideal, unless there's plenty spare.

As for programming an Arduino Mega in C++, I can understand that many might see this as a folly. But it's what I'm quickest doing development in and anyway, why have layers of abstraction if one can't work at the level they want. :wink: (If exceptions were enabled for the compiler for the chipset, I'd be fully using the boost C++ libraries...)
I've also been using the QP state machine framework for the project, which really has made things easy, but of course takes up more RAM.

Anyway, there you have it. Hopefully my efforts for this shield are of use to other developers.

Colin

http://www.lagrangianpoint.net
http://www.aethersdr.org

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brad
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Re: New: Arduino Mega SRAM expansion shield kit

Post by brad » Sat May 11, 2013 8:32 pm

Thanks very much for the info Colin, and nice work on the expansion shield by the way!

I have only had a little bit of experience with C++ which was back in 1999. I guess I have slotted myself into a few flavours of basic like swordfish basic, visual basic and am starting into firewing (basic) It's fun to stick with what you know best :)

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