Where to start


6 posts
by Miksture » Tue Jun 26, 2012 6:13 am
Hi,

I have been a software developer for many years, even some of them working in unix and xenix (old). One thing I have done only a little on is low-level programming for devices. I did some work talking to serial cash registers using a possum board in the 1980's and some using rs-232 to talk to light switching and solenoid devices around the same time. Now that my son and I have a raspi we are wanting to try a few things out.

  • What advice do you have for someone new to using a computer to control devices?
  • How hard is it to operate low current relay styled switches for example to operate a solenoid?
  • I realise that raspi sends digital signals out of the GPIO pins but is that enough to trigger something like this? Eg hold a relay open for 0.1-0.5 seconds?
  • Also, how do boards like the MaKey MaKey work as a way to sense events for a raspi? I believe the MaKey MaKey converts a contact to a key stroke. It can apparently act to operate motors etc. Exttract from their site http://www.makeymakey.com/:

    You could say this board is 2 in 1. MaKey MaKey runs on top of Arduino. You can start using your MaKey MaKey board in "Arduino mode" at any time. This would allow you to spin motors, turn on LEDs, or anything else that an Arduino can do. If you want to learn to use Arduino or other electronics, but want to start without any programming or breadboarding, MaKey MaKey is a good starting point. There's no need to understand Arduino in order to use MaKey MaKey.
  • Is Arduino something that is commonly used? Can raspi use it?

Any pointers are appreciated.
Posts: 1
Joined: Tue Jun 26, 2012 5:58 am
by Ravenous » Tue Jun 26, 2012 8:56 am
Have a look at the glockenspiel-thing on the News page at the moment - that has some interfacing details for his buffer board.

I think you could also use an arduino (or any other microcontroller) to do low-level stuff, so you send it serial, I2C, SPI or whatever and it does the low-level control via its output pins. Depends how intensive the device control is (for example, accurate speed control of a motor, etc.)
Posts: 1601
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK
by ksangeelee » Tue Jun 26, 2012 10:28 pm
Miksture wrote:[*]How hard is it to operate low current relay styled switches for example to operate a solenoid?

[*]I realise that raspi sends digital signals out of the GPIO pins but is that enough to trigger something like this? Eg hold a relay open for 0.1-0.5 seconds?

Any pointers are appreciated.


I've just written up some notes on driving a relay (here) from a GPIO pin on my Pi - there's very little to it, just a relay, a transistor, a resistor, and a diode (costing less than a pound in total).

A relay coil will almost certainly require more current to operate than a GPIO pin can ever provide, but it provides enough current to switch on a transistor to drive the coil.

(by the way, your subject title is way way too vague - you'll get more responses if you use more specific titles; and you a software guy too, tsk! :o )
.
Posts: 193
Joined: Sun Dec 25, 2011 5:25 pm
Location: Edinburgh, UK
by eldiabolosk » Wed Aug 15, 2012 4:40 am
I am also a newbie. Does anybody know a good link or even a book where to start, read up, get ideas and excitement?
I am Linux savvy, but know almost nothing about electronics.

ed.
Posts: 14
Joined: Wed Aug 15, 2012 12:27 am
by danpeirce » Fri Aug 17, 2012 6:28 am
eldiabolosk wrote:I am also a newbie. Does anybody know a good link or even a book where to start, read up, get ideas and excitement?
I am Linux savvy, but know almost nothing about electronics.

ed.


Taking your comment and your question at face value I would say that basic circuit theory is essential to understanding device and module sesifications. You could start with this for basic theory: http://www.allaboutcircuits.com/vol_1/index.html

In many respects getting projects up and running is a lot more straight forward than it was in the 1980s. Many sensors are available as modules and motor drive circuits are available as modules or ICs. Local suppliers of arduino board will most likely have a lot of sensor and driver modules available.
User avatar
Posts: 88
Joined: Thu May 10, 2012 8:32 am
Location: Richmond & Surrey BC Canada
by 9mgibson » Fri Feb 08, 2013 3:43 pm
Hi, I am a complete newbie to Pi, Linux Etc. Take a look at http://www.phidgets.com/ These are a little more expensive than MaKey MaKey, but can do a lot more. I got the stepper controller working within two days of my Pi arriving. :)
Posts: 1
Joined: Fri Feb 08, 2013 3:33 pm