Which board?

The "Eleven" is our Uno-equivalent Arduino-compatible board, but with a number of improvements including prototyping area, a mini-USB connector, LEDs mounted near the edge, and the D13 LED isolated using a FET. [Product page]
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timmyc
Posts: 2
Joined: Sat Aug 24, 2013 10:00 pm
Location: Gisborne, New Zealand

Which board?

Post by timmyc » Sat Aug 24, 2013 10:49 pm

Hi all,

Noob question here...
I'm fairly new to Arduinos, although I have a bit of electronics background, so hopefully that'll help me a bit.
I've had a play with a couple of Eleven boards, LCDs and DMDs, and am coping well so far, although to be honest it's been more cut-and-paste then modifying from other examples, rather than writing my own sketches. The hardest bit is trying to think like a microcontroller thinks :)

I'm about to embark on my next project, which is a bit more complicated, although I wouldn't have thought it to be overly complex...

Basically, it's a 10 way timer, which is reading data via serial, and then driving LED's to indicate. But I'll need 20 LEDs, and 10 Switches for individual resets, plus a master reset switch. I'd also like to log every action to SD card, so possibly need an RTC module as well, to make time-stamped recordings.
So really I'm looking at:
20x Outputs
11x Inputs
plus SD card
plus RTC module
and serial connection (onboard USB/serial is fine).

My main question is should I try to do it all with an Eleven, by multiplexing or using IO expanders. Or should I be looking at using an EtherMega with the additional I/O pins, and using the discrete outputs for LEDs and switches?
I can see the advantage of the EtherMega (or even EtherTen) with the onboard SD slot, but are there any other advantages/disadvantages either way? I have an Eleven sitting around at the moment, but price isn't too much of an issue at the moment if it's worth going with a different board.

Thanks in advance,
Tim

andrew
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Re: Which board?

Post by andrew » Sun Aug 25, 2013 5:58 am

The physically much simpler option would be with an EtherMega and a RTC.

Otherwise use a few MCP23017 I/O expanders and a microSD card shield/adaptor.
http://www.microchip.com/wwwproducts/De ... e=en023499
http://tronixstuff.com/2011/08/26/tutor ... -io-ports/

Another options would be to "charlieplex" the LEDs and use a couple of analogue inputs to read multiple buttons, or use a numeric keypad. There's really quite a few methods to do what you want, it comes down to your experience and how you like doing things.

timmyc
Posts: 2
Joined: Sat Aug 24, 2013 10:00 pm
Location: Gisborne, New Zealand

Re: Which board?

Post by timmyc » Sun Aug 25, 2013 9:16 am

Thanks for the reply.
Those MCP23017's look like they'd do the job nicely, so I'll get some from Element14 and see how I go.
If that fails, I'll try a Mega :D Any excuse to play with new toys.....

andrew
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Re: Which board?

Post by andrew » Mon Aug 26, 2013 12:19 am

timmyc wrote:Thanks for the reply.
Those MCP23017's look like they'd do the job nicely, so I'll get some from Element14 and see how I go.
If that fails, I'll try a Mega :D Any excuse to play with new toys.....
They're an easy part to use, you'll be fine :)

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