schmitt
Posts: 9
Joined: Mon Sep 17, 2012 7:32 pm

Number of stepper motors, LCDs and LEDs feasible with RP

Mon Sep 17, 2012 7:40 pm

Hi there,
I'm intending to start a project that involves a number of hardware outputs. As planned now, it would need two stepper motors, one servo, an LCD display, a few buttons and (optionally) a bunch of LEDs.

Is it feasible for me to drive all that with a Raspberry Pi? I understand there aren't enough GPIO pins to do all of that, is there some way I could get around the limitation by multiplexing or something? I don't have any experience with that sort of thing, could anyone point me in the right direction?

Of course I may be trying to shoehorn the Pi into a job it's not really suited to. Should I just use an Arduino Mega or something instead?

Thanks a lot,
Alex

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johnbeetem
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Location: The Mountains
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Re: Number of stepper motors, LCDs and LEDs feasible with RP

Tue Sep 18, 2012 8:41 pm

I think it depends a lot on your software. If it's a big program with file I/O and a graphics display, RasPi running GNU/Linux is a good platform.

OTOH, if your software is of modest size and doesn't use file I/O or a graphics display, something like the STM32F4DISCOVERY (http://www.st.com/internet/evalboard/pr ... MENT_TOOLS) might be a better match. This is particularly true if you need to access your devices at the bare metal and need real-time response.

schmitt
Posts: 9
Joined: Mon Sep 17, 2012 7:32 pm

Re: Number of stepper motors, LCDs and LEDs feasible with RP

Wed Sep 19, 2012 7:28 pm

The program will be pretty complex and my main motivation for using a Pi was so I could do it in Python. It isn't going to have a monitor style output, only a small LCD text display. Timing isn't critical, I'm just concerned that the number of outputs and inputs is going to be too limited.

techpaul
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Location: Reading, UK
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Re: Number of stepper motors, LCDs and LEDs feasible with RP

Wed Sep 19, 2012 10:02 pm

Depending on size of LCD text display required there are plenty of I2C built in displays about

I2C and SPI can be used to add hundreds of I/O if they are not time critical.

Worse comes to worse get to learn how to programme a small 8/16/32 bit micro that has I/O that can then be timed accurately then feed that via UART or whatever to/from Pi.

It is just the same for any computer system, even the "PC" has lots of other microcomputers inside doing dedicated functions from keyboard, via hard drives and DVDs to graphics processors.
Just another techie on the net - For GPIO boards see http:///www.facebook.com/pcservicesreading
or http://www.pcserviceselectronics.co.uk/pi/

schmitt
Posts: 9
Joined: Mon Sep 17, 2012 7:32 pm

Re: Number of stepper motors, LCDs and LEDs feasible with RP

Thu Sep 20, 2012 8:42 pm

Thanks a lot guys, I think we're going to do something like that.

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rew
Posts: 423
Joined: Fri Aug 26, 2011 3:25 pm

Re: Number of stepper motors, LCDs and LEDs feasible with RP

Mon Oct 01, 2012 1:02 pm

We have the LCD and stepper motor drivers as plug and play. :-)
Add a DIO boardand you can add the buttons.
There aren't really any limits to how many of these you can connect. Without any trickery you can add 120 I2C bords, and 240 SPI ones... You will have to make arrangements for power distribution. :-)
Check out our raspberry pi addons: https://www.bitwizard.nl/shop/

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