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[on:]

Hi

First up, im a complete newb on Arduino, but from what i've read/researched on it does look very promising.

I want to start out with a Basic Home Automation project to control some lights appliances in my house at first, have this communicate with my Android phone via Bluetooth, eventually with a app ill write specifically for my needs.

**Now my first question is what Arduino board to get:
Im looking at either the Mega2560 R3 or the Uno R3, as this project could grow quickly with alot of input/outputs for appliances etc i thought it might be worth it to go for the Mega first up, is this wise?

Then for a bluetooth module, i really want to see what i can cook up before going the shield route, i thought about getting this:

Product Feauture:
This module is preassembled bluetooth module which is ready for use to connect any MCUs,ARM,DSP,FPGA and arduino board, and it provide short length wireless communication with each other or laptop. User only need to connect the signal to the standard TTL UART port and use AT command to configure the working mode, then you can transiver user data transparently.
Note: This module is 3.3V standard TTL voltage level.
Package include:
1x TTL Bluetooth Module
1x adapter board for Bluetooth Module
5x 10cm fly wire cable
Email support for user guide and AT command
http://www.ebay.com/itm/1pcs-TTL-Bluetooth-Module-adapter-board-arduino-/270933615210?pt=LH_DefaultDomain_0&hash=item3f14e6e26a
**Is this an "OK" choice?

Any advice will be greatly appreciated.

[Reply #1 on:]

Hi

I've no experience with this particular unit, but would draw your attention to the 3.3V signal levels on it.  Uno and Mega boards are usually 5V (usually, there are 3.3V flavours too) so that will mean a logic level converter needs to also be in your shopping list.

Something like this will do the trick http://www.sparkfun.com/products/8745

Cheers !
Geoff

[Reply #2 on:]

Ah ok thanx, but in theory it should be sufficient? Ive noticed a couple of these Bluetooth adapters have a 3.3-6v range, others 3.3v or 5v.

Should i go straightup for the Mega?

[Reply #3 on:]

Ah ok thanx, but in theory it should be sufficient?

Yes it should be fine (based on my 100% lack of experience with that unit )

Should i go straightup for the Mega?

Your call entirely.  If you want to go for the mega and when the project's done you find you could have based it on a Uno there's nothing to stop you swapping a cheaper Uno into place, loading the sketches and strapping it into your enclosure; and conversely if you start with a Uno and run out of pins you can either upgrade to a mega, or there's ways of adding inputs, outputs, PWM pins etc with additional ICs and circuitry.

You'll find the Arduino ecosystem is nothing if not flexible. 

All the best with your project, Geoff

[Reply #4 on:]

Just a short note : I have also started a home automation / alarm system and you may want to consider this :

with a BlueTooth device, you have limited range.

If you instead add an ethernet shield on top of the Mega, and connect to a DSL line / router, you can have the Mega serve up a web page that you can access from your PC web browser or phone browser, from anywhere, with on/off switches for each item. You can arm / disarm the system, turn things on and off when you want away from home.

The same code can also be used to send info from your Mega to a text file stored on the internet. So you can log temperature readings, on / off or door contact readings all to your off site web server text file. A simple php page on the same server allows you to view that log file, again from anywhere that you have web access.