Arduino Forum

Topics => Home Automation and Networked Objects => Topic started by: Mikee on Jan 10, 2013, 02:08 pm

Title: Cheap and small RF Rx/Tx
Post by: Mikee on Jan 10, 2013, 02:08 pm
Hi everybody,
I was wondering in somebody used one of these:
http://www.aliexpress.com/item/Free-Shipping-10pair-lot-433MHZ-Superregeneration-Wireless-Transmitter-Module-Burglar-Alarm-and-Receiver-Module/686618396.html
(http://www.aliexpress.com/item/Free-Shipping-10pair-lot-433MHZ-Superregeneration-Wireless-Transmitter-Module-Burglar-Alarm-and-Receiver-Module/686618396.html)
I want to make some RF sensors and remotes for my arduino but cheap. I need to send and receive only On/OF (0/1) signal to and from arduino. I have no idea about coding for RF (I hope Transmitters and receivers will be paired).
My vision is:
After signal Input (+5) on DATA at transmitter (Sensor version) will be end signal to Receiver and that I can read on digital port through Arduino.
Will it work this way?
Title: Re: Cheap and small RF Rx/Tx
Post by: johnwasser on Jan 10, 2013, 03:38 pm
Quote

After signal Input (+5) on DATA at transmitter (Sensor version) will be end signal to Receiver and that I can read on digital port through Arduino. Will it work this way?


I think those transmitters/receivers use ON/OFF Keying (OOK).  When the transmitter data pin is HIGH it transmits.  When the data pin is LOW it turns off.  Similarly, if the receiver detects a signal it turns the output pin HIGH and if it doesn't detect a signal it turns the output pin LOW.  If the two are close to each other and there are no other transmitter in the area using the same band the output of the receiver should be similar to the input of the transmitter.

There is a library called "VirtualWire" that adds framing around your message so that it can detect interference.  This can be used to prevent damaged messages from causing unexpected behavior on the receiver.
Title: Re: Cheap and small RF Rx/Tx
Post by: llukkari on Jan 10, 2013, 03:45 pm

There is a library called "VirtualWire" that adds framing around your message so that it can detect interference.  This can be used to prevent damaged messages from causing unexpected behavior on the receiver.


Documentation for VirtualWire can be found here: http://www.open.com.au/mikem/arduino/VirtualWire.pdf

This migth help also: http://code.google.com/p/rc-switch/. You could use the same protocol and use those kinds of remotes to controll it along with your arduino.
Title: Re: Cheap and small RF Rx/Tx
Post by: Mikee on Jan 11, 2013, 07:10 am
Thanks Guys!, really helpful comments, I´m ordering Today?
Btw. Llukkari, great job with your web interface, maybe one I'll get there too.
Title: Re: Cheap and small RF Rx/Tx
Post by: robitabu on Jan 11, 2013, 04:46 pm

Hi everybody,
I was wondering in somebody used one of these:
http://www.aliexpress.com/item/Free-Shipping-10pair-lot-433MHZ-Superregeneration-Wireless-Transmitter-Module-Burglar-Alarm-and-Receiver-Module/686618396.html
(http://www.aliexpress.com/item/Free-Shipping-10pair-lot-433MHZ-Superregeneration-Wireless-Transmitter-Module-Burglar-Alarm-and-Receiver-Module/686618396.html)


Those modules are very easy to use with the VirtualWire library. Go get it. It lets you send short data packages, enough for your purpose.
Don't expect long distance range, the signal will suffer because of every obstacle you put inbetween.
I used them at home, they cover some 10meters w/ obstacles. Much depends on the power supply too (higher voltage makes them cover higher distances).