XMEN BLOGGER: Raspberry Pi - WiringPi with RF 433mHz transmitter

WiringPi GPIO pins

Pin 2 - Vcc (5V)
Pin 6 - GND
Pin 11 - GPIO 17 - (WiringPi Pin 0): Linked to Emitter
Pin 13 - GPIO 27 - (WiringPi Pin 2): Linked to Receiver (RF433MHz – XY-MK-5V)

FROM: http://i-build-stuff.blogspot.com.es/2015/01/wireless-room-temperature-monitoring_27.html

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


Code 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 :


pi@raspberrypi ~/wiringPi $ gpio readall

(*) Raspberry Pi RF remote (433MHz)

FROM: http://npham.dk/?p=34

Creating RF transmitter / receiver

Source: http://shop.ninjablocks.com/blogs/how-to/7506204-adding-433-to-your-raspberry-pi

I bought my RF transmitter and receiver from eBay a about 1$.
Connecting RF transmitter and receiver to the Raspberry Pi is pretty simple.
Both the reciver and transmitter has a VCC, GND and DATA pins.
And all you do is connect it to the Raspberry Pi GPIO pins.

Install RPi_utils

Source:
https://github.com/ninjablocks/433Utils/tree/master/RPi_utils

Start by installing RPI_utils


sudo apt-get update

#Installs GIT


sudo apt-get install git

sudo apt-get install git-core

#Installs 433utils


git clone git://github.com/ninjablocks/433Utils.git

cd 433Utils/RPi_utils/

#Installs wiringPI


git clone git://git.drogon.net/wiringPi

cd wiringPi

git pull origin

./build

#Builds RPI_util


cd ..

make all

Testing and decoding RF signal

To capture and decode the RF signal from the remote, I ran the program RFSniffer.


sudo ./RFSniffer

When I push the A (on) button on the remote, I get the following code on the screen.


Received 5260625

Received 5260625

Received 5260625

Received 5260625

Received 5260625

To test if the transmitter works you can send the received value with this command.


sudo ./codesend 5260625

If you convert 5260625 to binary, you get 10100000100010101010001.
And looking at the binary value of all the buttons, you start to see a pattern.


Button Decimal value Binary value

A (On) 5260625 10100000100010101010001

A (Off) 5260628 10100000100010101010100

B (On) 5263697 10100000101000101010001

B (Off) 5263700 10100000101000101010100

C (On) 5264465 10100000101010001010001

C (Off) 5264468 10100000101010001010100

D (On) 5264657 10100000101010100010001

D (Off) 5264660 10100000101010100010100

They all starts with 1010000010, and all the ON buttons ends with 0001 and all the OFF buttons ends with 0100.
The 1010000010 matches with the dip-switches; 10 = down and 01 = up.
The middle part, is a value that identifies A,B,C and D.
You can see the pattern here:


Dip switch Button Id On / Off

A = 10 10 00 00 10 + 00 10 10 10 1 + 0001 / 0100

B = 10 10 00 00 10 + 10 00 10 10 1 + 0001 / 0100

C = 10 10 00 00 10 + 10 10 00 10 1 + 0001 / 0100

D = 10 10 00 00 10 + 10 10 10 00 1 + 0001 / 0100

Script

I then created the following bash script.


#!/bin/bash

BTN=$1

STATUS=$2



BTN=$(echo $BTN | tr '[:lower:]' '[:upper:]')

STATUS=$(echo $STATUS | tr '[:lower:]' '[:upper:]')



DIP_SWITCH="DDUUD"  #Change dip switches to match the remote



#hardcoded values

BTN_A="001010101"

BTN_B="100010101"

BTN_C="101000101"

BTN_D="101010001"



DIP_SWITCH=$(echo $DIP_SWITCH | sed 's/D/10/g' | sed 's/U/00/g')



case $BTN in

    A )

        BTN=$BTN_A ;;

    B )

        BTN=$BTN_B ;;

    C )

        BTN=$BTN_C ;;

    D )

        BTN=$BTN_D ;;

    * )

        echo "Please define the button [A-D]";exit;

esac

case $STATUS in

    ON )

        STATUS="0001" ;;

    OFF )

        STATUS="0100" ;;

    * )

        echo "Please define the button state [ON/OFF]";exit;

esac



BIN=$(echo $DIP_SWITCH$BTN$STATUS)

DEC=$((2#$BIN))



#echo $DEC

sudo /home/pi/codesend $DEC

And to emulate a click, I just call


./RFISend.sh A ON

Control via web

Because the codesend uses wiringpi, it is required to call with sudo.
But if you need to call it from a webserver, it creates some problem, because sudo requires a password.

So we need to edit visudo, so it doesn’t require a password.
(it may not be a secure thing to do, but in my case the webserver is not exposed to the internet, and is only for “at home” use)


sudo visudo

Add the following line to the file.
#NOTE: use TAB and not space, except for the last one – after NOPASSWD:


www-data        ALL=(root) NOPASSWD: /home/pi/433Utils/RPi_utils/codesend

Save the file and reboot the Raspberry Pi, and you’re good to go.

Now the local PHP webserver can call the script with:


< ? php

  shell_exec("/home/pi/433Utils/RPi_utils/RFISend.sh A ON");

? >

http://rsppi.blogspot.com.es/2013/08/comunicacion-por-rf-433mhz-desde.html

Home Control Dashboard
https://dendriticspine.github.io/projects/2014/10/10/homedashboard

REFERENCE:

http://www.touteladomotique.com/forum/viewtopic.php?f=118&t=15760

http://wiringpi.com/wp-content/uploads/2013/03/pins.pdf

WiringPi GPIO pins
http://www.14core.com/configure-clibrary-wiringpi/

http://blogwifi.fr/raspberry-pi-b-telecommande-433-mhz-universelle/

http://domotique-home.fr/domotique-diy-partie-2-protocole-433-mhz/

http://npham.dk/?p=34
http://www.princetronics.com/how-to-read-433-mhz-codes-w-raspberry-pi-433-mhz-receiver/