[Wireless Room Temperature Monitoring System] How to test the 433 Mhz RF Module (Receive / Transmitter)

I started to receive some of the parts that i ordered. Unfortunately i didn't receive enough to start the project.

Fortunately what i received already can be tested. I received my 5 pairs of RF 433 Mhz modules (RX / TX), jumper cables and some small breadboard, with the Raspberry Pi i already had ... i can cook :)

The idea here is to be able to test the modules in order to see if all 5 pairs work properly (since they were crazy cheap and sent from China)

The strategy here is to use the Raspberry Pi as the sender and the receiver.

First i had to install WiringPi in order to have the GPIO working properly
Then i had to install 433Utils, a neat little module that is allowing me to receive (sniff) and send data.

For the wiring i use a breadboard to power both RX and TX modules using the 5V pin 2 and the GND pin 6.
Then i use cables to connect the RX/TX modules data pins :

• Emitter : Pin 11 (GPIO 17) of the Raspberry Pi. Also marked as Pin 0 under WiringPi's naming convention)
• Receiver : Pin 13 (GPIO 27 Rasp Pi B+). Also marked as Pin 2 under WiringPi's naming convention)

With that simple setup on i can go ahead i can try and send data and see if it is being received.

Now on my computer i connect to my Raspberry Pi using ssh

Code 1 : ssh pi@yourlocalIPaddress  (once prompted, enter your password. Default is "raspberry") 

Then i have to go to the specific folder where the 433Utils programs are stored in order to start them.

Code 2 : cd 433Utils/RPi_utils

This bring you to the correct folder where the sending program and the sniffing program are stored.

Now i open another Terminal window and login via ssh (code 1) and i go to the 433Utils folder (code 2)

In the first terminal window start the Sniffer program.

Code 3 : sudo ./RFSniffer

Now in the second terminal window send a code

Cod 4 : sudo ./codesend 121234 (any random integer)

If everything works fine, you should see your integer going through the Sniffer result window just like in the below screenshot :

I noticed that i couldn't send more than 8 digits for that integer.

This is my first victory with this stuff that i never used before as i am not in electronics at all.

Now i have been trying to mess-up with it and tried to "sniff" different 433Mhz RF Remotes in order maybe to know what was the sent signal and use the Rasp Pi as a replacement remote.

I tried with 2 differents things. 

• A RF wall plug remote (Brand QUIGG), the user can't really do anything with the remote (no channel selection or anything like) ... whatever i tried ... no signal was picked up.
  
• A RF Remote for an automated garage door from my building. Same thing here ... no luck in picking the signal from the remote ...
  

I read in many place that the only of "reading" the signal from a remote was to use a jack and soundcard in order to "see" the pattern of the signal and reproduce it. Anyone have any idea how this works ?

[Wireless Room Temperature Monitoring System] The plan

Now that all the parts are ordered i am basically waiting.

I decided to utilize that time and draw a small sketch of how i plan to connect the multiple elements of my project. Basically it looks like that
Key
Orange = positive current
Lines = negative
Stripes = data

What do you think ? Am i making any mistakes ?

[Wireless Room Temperature Monitoring System] Component Choice

In order to build the system i thinking of using the following :

For the sensor :

• Arduino Mini Pro 5v

• DS18B20 Module for temperature detection

• Emiter RF 433 Mhz

• Antenna
• 9V Battery Case

For the computing system :

• Raspberry Pi B+

• Receiver RF 433 Mhz

• Antenna
• Wall Plug Power Source
• Wifi Dongle

In order to program the Arduino Mini Pro i think i will go with a USB to TTL serial adapter FT232RL.

I am about to order all those parts online...

[Wireless Room Temperature Monitoring System] Detailed Requirements

Amount and location of the sensors needed :

• Bedroom #1 (expected temp range : 15 to 25 C)
• Bedroom #2 (expected temp range : 15 to 25 C)
• Living Room (expected temp range : 15 to 25 C)
• Balcony (expected temp range : -20 to 40 C)
• Fridge (expected temp range : 0 to 10 C)

Optional (for later)

• Cooking temp sensor (Solid Food, Liquids, Pastes) (expected temp range (0 to 250 C)

The temperature sensors must be wireless and have a good autonomy.
The distance range must be around 50 meters to 200 meters. This system will be used in an apartment of 70 meters square and must be usable in bigger houses as well.

[Wireless Room Temperature Monitoring System] - Goals and Requirements

The aim of this project is to build from scratch a Monitoring System that would allow me to monitor remotely (from a main station or online) the temperature within several rooms inside my apartment, as well as the outside temperature and ultimately the temperature in the fridge.

The goal is to build that as cheap and as simple as possible.

I personally do not have any skill in the relevant technical domains (programming nor electronics) and i start this as a personal challenge to see if i am capable of doing it … and also because i really want to have such a system in place.

This site is there to document my thoughts, challenges and progress.

I hope this will be useful to other Makers in the future.