choosing a microcontroller for my project...help!

[icydash]

Hi! So I'm trying to design a circuit where on one end, if i hit a regular push button switch, it causes a wireless signal (maybe the word "turned on" if the switch is on, or "turned off" if the switch is off, using perhaps a zigbee?) to be sent to a wireless receiver on the other end. The wireless receiver then sends the data to a microcontroller, which decides what to do based on if it receives the "turned on" or "turned off" signal.

If it's "turned on," the microcontroller will allow a [guitar signal] to be conducted through one wire/path, and if it's "turned off" it will direct the guitar signal through a default path (another wire).

I'm not sure what microcontroller to use. I want the receiving end to fit in the smallest possible case. Literally, if I can do the whole thing in something the size of my thumb, etc, that would be fantastic. I was hoping people could provide me with easy to use microcontroller options, etc. That would be extremely useful since I'm not that aware of what's out there. Since the processor is doing minimal work, nothing fancy is needed. The simpler the better. I guess the smallest microcontroller unit that is still solderable and easy to prototype with is what i'm looking for. Cost / money is not an issue.

Thanks so much!

PS. If you have any good ideas about a wireless chip to use, too, that would be extremely helpful. Is there anything more suited to this kind of application than a zigbee (this is all i know of)?

 

[IanP]

At both ends you may use PICAXE-08 and el-cheapo 433MHz Tx-Rx pair ..
Similar project was discussed here:


Rgds,
IanP

 

[icydash]

thanks for the quick reply! I have a few questions:

So I'm looking at the modules on:
http://robokitsworld.com/index.php?main_page=product_info&products_id=75

Up top in the main first picture of the modules, it seems like the transmitter is the shorter module on the left, and the receiver is the longer module --- this sized receiver is going to be too big. If they where both the size of the transmitter then it'd work fine--why is the receiver so big? If you scroll down to about half way down the page, they show another transmitter/receiver pair that appear to be the same size-ish, which seems more like what I'm looking for....though I can't seem to find those anywhere and the data sheets are just for the bigger receiver/transmitter pair.

Also, they both seem to take external antennas and say no where on the datasheet if they have internal antennas. An internal/on board antenna would definitely be preferable since it saves space--do these modules have on board antennas and just not say it?

Thanks again!

 

[wp100]

Hi,

I bought a pair of those ASK boards from Sparkfun the receiver board is only 43x12mm, is that too big ?

The data sheets I got say use about 250mm of single core wire as the antennas for covering large distances, but if you are using it at short range you might get away with none.
The tx unit will work from 5v up to 12v if you need to boost its output.

Be aware that you must use Manchester coding with them as the airwaves are full of 433 signals that will swamp your receiving micro as I found out when I scoped the receivers output.

 

[icydash]

Hi! thanks for the reply! Yeah unfortunately 43mm (plus the amount of space i'd need for the antenna wire) would be too long. I want to have all the circuitry combined in the smallest possible space (if i can maybe 25mm by 25 mm).

What is manchester coding? and thanks for the heads up on the 433 signals.

 

[wp100]

Hi,

If you see this link it explains the Manchester coding method / reasons.
That link also points to the codes originator although its only in assember, some searching should show it in C.

Also when testing you will probably put the tx in a tight transmit loop like I did -don't - took me a while to realise why I could not open the car door - the continuous signal was jamming my car remote !

 

[icydash]

interesting and good to know.

would i be better off using like zigbees? they seem pretty cheap and small and i don't need any special coding for them, correct?