[Noisebridge-discuss] Wireless relays + sensors

Taylor Alexander tlalexander at gmail.com
Mon Feb 18 09:49:33 UTC 2013


FWIW I'm working on a cheap wireless arduino module that I should have done
by the end of a hackathon next weekend. It would be a complete arduino and
wireless solution integrated into one compact board. My main goal is
wireless lighting control, but it will be general purpose enough to control
other things (and open source so you can always modify it). It uses the
CC2500 2.4GHz wireless chip, which is under $3 in qty 100 and $4 qty1. So
it should hopefully be great for making many wireless nodes for cheap. I
just got basic communications working, so the concept works. I'll do the
rest of the work at the Hackathon.


On Sun, Feb 17, 2013 at 3:28 PM, Jake <jake at spaz.org> wrote:

> Hi Carlo,
>
> I recommend the arduino platform.  It is pretty easy to code in arduino's
> flavor of C (basically just like regular C except less pedantic) and the
> hardware has all the things you need.  Six analog inputs and 13 GPIO
> General Purpose Input/Output pins.
>
> If you're going to be controlling things running off of DC power, you can
> simply use an N-channel FET connected between the output pin of the
> arduino, Ground, and the minus terminal of your pump or motor or whatever.
>
> If you're going to control things powered by 120V (or 240V) AC power, you
> need an opto-isolated SCR relay, or if you prefer you could use a regular
> coil-style relay.  If you use the former, you just connect it to the
> arduino output in and arduino ground, and the other side of it has two
> screw terminals that go in series with the AC load.  Very simple and you
> could control a 5KW water heater if you wanted to.
>
> As for sensors, to use a thermistor temperature-sensor you just wire it to
> one of the six analog inputs with a pull-up resistor, and read the value in
> software.  There are also digital and analog temperature sensors you can
> get from mouser or digikey which require no calibration and send
> temperatures in numbers of degrees either through digital protocols or by
> sending a DC voltage to your ADC.
>
> I can't see why you would need a raspberry pi for this unless you needed a
> web interface.  If you did, I would recommend considering the WR-703N which
> is smaller than a raspberry pi, half the price, and has a 500mW wifi radio
> built in.  And it has GPIO pins you can use to control stuff, although it
> would be easier to just plug an arduino into its USB port.
>
> -jake
>
>
> Carlo wrote:
> I bet something similar has already been discussed :) but...
>
> I want to control a few water pumps (low power, aquarium kind of
> pumps) via software, and read inputs from a sensor or two (humidity,
> temperature).
>
> I'd like a solution that is cheap, I can bring up as quickly as
> possible with as little work as possible, ideally no to little
> soldering, I can easily program with good libraries (python / C /
> whatever is fine). Eg, I'd like this to be a one afternoon project, I
> plan to get most of my hacking fun by playing with the result, rather
> than with building the system :)
>
> I was looking into:
> 1) raspberry PI + relay board + sensors.
> 2) Arduino + relay board + sensors - seems like a bit more work than
> the above? even if more flexible?
> 3) Something like:
> http://www.controlanything.**com/Relay/Relay/WIFI_PROXR&**
> CpField=relays&CpValue=4<http://www.controlanything.com/Relay/Relay/WIFI_PROXR&CpField=relays&CpValue=4>
> they seem to have tons of pre-made relatively low effort solutions.
>
> I've had some embedded experience in the past, but have not used any
> of the above. Suggestions? hints? experiences?
>
> Thanks!
> Carlo
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