What RF modules for wireless LED pwm control?


1 post
by PineappleJoern » Sun May 26, 2013 11:59 am
Hi guys,

I've been working on my very first Pi project. I'm trying to build a home lighting system with functionality similar to Philips 'hue' smart light bulb system - i.e. colour mixing via PWM signals from the GPIO pins.

I'm building my own lights with High Power RGB LEDs whose control circuits are connected via wires to the GPIO pins. But I'd love the system to be wireless to allow for simple light arrangement, hassle free setup and for extra awesomeness factor.

How could I build an affordable, scalable wireless network of lights connected to and controlled via the Pi? I study Computer Science but I'm pretty bad when it comes to low level stuff like this.

The implementation should be small in package size and hardware setup. Disregarding the setup price of turning the Pi into a wireless base, I'd like to aim for a price of the wireless modules for one light below 20 USD. (A Philips hue bulb costs 60 USD, I'd like to stay 'competitive' with that with my far inferior lamp hardware :roll: )

My ideas were:
1) Arduino + Bluetooth
Seems the simplest solution for me regarding ease of configuring such system to receive commands from the Pi and create PWM signals accordingly, thanks to good documentation and libraries.
But its very bulky, Arduino needs extra power, and the setup might be slightly overkill to just drive a single light. I'd actually like to go more "low level" than this to learn more about embedded systems.

2) Zigbee Modules
Philips uses the IEEE 802.15.4 in 'hue' themselves and I read this is a generally good choice for wireless home automation. But I don't exactly know what hardware I'd need, how to let the Pi transmit data with the ZigBee protocol and how to generate PWM signals at the lamp.
Would this ZigBee wireless module be a thing for the receiving side at the lamp? http://www.fasttech.com/products/0/1000 ... le-with-an

3) XBee
XBee modules appear to be more accessible and programmable for Arduinos (Pi's). They are quite pricey at above 22 USD a piece though, e.g. http://www.adafruit.com/products/128
What components would be necessary to build a Pi controllable network of such transmitters?

How would I create the PWM signals at the lamp when the wireless module receives the "pwm command"? Are there any low budget microchips that could process such commands - which can output 3 configurable PWM signals with a high range and resolution of duty cycles ( 0 to 100% in 1% steps or similar) ?

Does anyone have experience with creating cheap wireless clients for the Pi? Could you provide me some guidance for what options are any good and doable?

Thanks for your help!
Jörn
Posts: 14
Joined: Mon May 20, 2013 10:26 pm