Single Receiver w/ 10+ Single Button Remotes

I want each remote to have a unique identifier, so the receiver/arduino knows "which" remote was pressed.

Hence the reason for multiple LED's...
The 10 LEDs will be on the receiver...

Each LED will have a matching remote.

Ever been on a teleconference call were two people say their name at the same time and you understand neither of them as they spoke at the same time?

Okay, well they only have 10 residents, so I don't really think that will be an issue..

How many milliseconds or seconds are we talking about the collide time?
My guess would be less than 100ms, right?

It's a small environment, so I don't really think that would be a problem.. If the unique ID of a remote don't match up, then the receiver will just ignore it... I think that should be fine...

For the residents, suggest making a simple circuit consisting of:
atmega168
8 MHz xtal, two 22 pf caps
10k reset resister
two 100nf caps on VCCs

(or a 3.3V/8MHz promini if you want to buy one)

LiPo battery
button
434 MHz RF transmitter,
http://www.robotshop.com/433mhz-high-sensitivity-transmitter-receiver-pair-rxa30.html
connector to plug in to a battery charge station every couple of weeks.

Minimal connections needed, hot glue the board into an enclosure, drill two holes to mount button and 1/8" mini jack for charging.

Short sketch consisting of button read to interrupt from powerdown sleep mode, virtual wire to send out a message, go back into sleep mode.

Base station will be similar, with LEDs/Buzzer. Powered on all the time listening for transmissions

Sounds like a fun weekend or two assembly project once the parts are obtained.

If you don't mind a little clunky looking, the Really Useful Boxes that Staples, Office Max carry are pretty durable and easy to work with. Add a couple of screws to secure the cover and not rely on the flip plastic handles.

I wouldn't worry about collisions - just have the transmitter send out its message a few times at differently spaced intervals from each other.

If the unique ID of a remote don't match up, then the receiver will just ignore it

So two people have pressed and you ignore them both? I would have thought a better strategy would be if you get an unidentified number the go check all 10 residents.
The other problem is that you probably can't guarantee 100% coverage 100% of the time no matter what the power of the transmitter. The antenna may be blocked or screened or at the wrong angle.

I have worked on alarm systems like this for a commercial company and it is not as straight forward as you might hope.

Without feedback - wont residents just keep punching the button until someone arrives?
With a two way system the base station would respond back to say "message received help is on it's way" and turn off the button until acknowledged. Having tried to teach numerous erm more senior family members how to use technology over the years, I've learned that the "mash the button as many times as you can" school of thought is the default setting. If this fails they fall back to "push the button harder" approach.

If you do go with those cheap transmitters - I'd strongly suggest that you ensure that they are FM based. I tried a couple of AM based ones a while back and they are terrible in terms of range.

True, maybe an LED that will light for a unknown ID.
Good idea!

But as for making my own remote, I could, but i'd rather not..
I'd rather use a keyfob remote from: http://www.linxtechnologies.com

As for collisions, I'll just add the LED for a Unknown ID.

Could always turn on an LED after the button press so they can see a message went out - make it flash or something distracting.

Those keyfob remotes look good too. Wonder how much.

Let me know on the pricing from Linx. If the can beat $22 each - I'll be giving them a call myself. :smiley:

I'll let u know once they open in like 10 minutes... I'll be calling them!

MS Keyfob Price: $17.95 Each
First Price-break is at 200 Pcs.

How much for the receiver?

Not sure, i just sent a email asking... I'll let u know once i know.

I have a suggestion for the transmitters I had a similar problem when looking for a pre-made remote's for a Traffic light system I made for loading bays in work, I came across "AM Keeloq" Transmitter's and receivers.

The transmitters are 1-4 buttons, they are Encrypted (keloq) so they cant be copied easily but more importantly they have a unique serial number which the receiver can read via a serial output the transmitter is designed for 4 buttons it has momentary or latch operation, basically a garage door opener, however as I've said the transmitter's have a serial number so it should not be hard to associate a specific transmitter with a specific task in your program.

oh the receiver has built in memory and can store 50 unique remote's (although you wont need to memorise them as you will be using the serial output)

The receiver costs $9.80 each. That's for the LR Module.

I'm not sure if i wanna go that route.. I don't need encryption, that would be overkill and more complicated for what i'm doing, and i don't have much knowledge in Wireless Technology to begin with.

The encryption is totally automatic you don't need to do anything the only thing you will be interested in on the receiver is the serial output which gives the transmitters serial number and which button was pushed.

The reason I picked this set-up was because it was cheap £15 for the receiver and £14 for the 3 button remote, the remote's with less buttons were cheaper (£10 I think for a 1 button)

I had a quick look at the receiver's on the Linx website that was linked ..correct me if I'm wrong but if you use those receivers you set the channel by DIP switches or hard-wiring the channel in, so you would need a receiver for every remote ?

zx

No, the price I posted was for the MS Keyfob (which uses a unique serial number)... The regular Keyfob uses the dip switches.