I am somewhat new to electronics (have always been on the software side), and I am trying to make a simple proximity detector. That is relatively easy, the problem arises when I want it to communicate with another room.
I was looking at this as a wireless device: http://www.sparkfun.com/commerce/product_info.php?products_id=8945
Will this transmit a simple current/no current signal if I just attach a wire providing current/no current to its data pin? All I want the reciever to do is light up an LED when there is no current.
Is this possible, or do I need to invest in a microcontroller?
That device is deigned to transmit bytes in a serial data stream. That’s not the way you want to use it. You’de be better off with a second hand wireless door bell.
Here is a simple system using the cheapie TX/RX units and a couple “decoder” chips. It is very basic, if you make a leg on the TX decoder chip, the corresponding leg of the RX chip goes high. No microcontroller programming, very few if any external parts. Wire it up and it works.
D’you think it would be easy enough to recognize what was going on inside the doorbell? After looking a little, I get the impression many of them throw in a lot of fancy stuff.
If I was theoretically to use a microcontroller, it would go on the reciever end? Or would I need two?
One odd thing though is that these are going for some insane price at some places…I don’t know why…I thnk I payed 21-25 for mine.
3 sensors, 1 base station that lights up depending on which sensor is triggered.
I’m currentl working on adding a picaxe 14m to the base station along with a transmitter to relay the info to a computer. I’ve also taken apart 1 of the sensors for experimention by removing the trigger mechanism and adding a line into it that I can connect to a breadboard.
The one i suggested does not need a microcontroller. Actually it is it’s own microcontroler(s) but there is no programming involved. Basically, the TX chip has inputs and each input is a “leg” of the chip (think of the chip as a centiped and it’s legs are well, the legs). These things work on 5 volts so when you make a leg “high”, it means you are sending 5v+ to that leg. --you could wire in a pushbutton or the output of your motion detector can click this leg “high”. (low means it is pulled to ground (-)) I think that the parallax PIR sensors go high when triggered.
When this or any other input pin goes high, the chip sends a code via the transmitter to the RX unit. From there it goes to the RX chip. The RX chip the makes one of it’s legs “high” and this pin corresponds to the transmitter’s pin.
In a nutshell. If input 1 gets 5v, output 1 puts out 5v. If input 1 is pulled to ground, output 1 goes to ground.
Those little RF Tx/Rx pairs are pretty handy. They’re very easy to use and once they’ve got power to them you can basically imagine that the ‘Data In’/Tx/Transmit pin on the transmitter is connected to the ‘Data Out’/Rx/receive pin on the receiver by some invisible wire - whatever signal you apply to the Tx is virtually instantly seen on the same Rx pin.
Just connect the output of the prox detector to the input of the transmitter unit, and have the output of the matching receiver unit drive an LED, either directly or through a transistor if you need more current than the receiver output can provide.
Now that I think about it, forget about the decoder chips. A 1 is a 1 is a 1, isn’t it.? If you just need a 1 or 0, the RX TX units should work fine as a stand-alone. Whatever the PIR is outputing will simply now output via the RX unit.
I hear ya. For me this removed some complexity that I didn’t want to deal with. Plus it was cheap for what it does. I would like to know more of how to build the sensors and reciever so that maybe I can build them myself…that would be the ideal…again though, this was an ideal solution for me.
The ones at sparkfun are just fine. We’re talking about a $5 part here --they are all the same and all come from China, doesn’t matter where you get them. Be sure to get a tx and rx and with the same freq.
As for spark fun, they are just simply awesome. The very best company I have ever done business with. Fastest shipping in the world, I swear. I don’t think you will find a single person here with a single complaint. Give your money to them.
My order just shipped and I should have it by friday…