SeaDoo4Life
Posts: 2
Joined: Tue Dec 08, 2015 11:45 pm

Wireless GPIO

Tue Dec 08, 2015 11:54 pm

Hello,

I'm wondering if anyone has attempted to do some wireless GPIO. I've done basic wired switches on GPIO ports that control lights and such. I'm trying to find information on how to just send high/low signals to the Pi, but wirelessly. I'd like to put some kind of RF transmitter in my doorbell on the ground floor to send a high signal when the button is pressed. I've taken the doorbell apart and have found voltage to power a transmitter, but I can only find serial modem type transmitters. I don't need anything as complicated as that, I just want it to act like if the button was physically connected to the Pi, so when the button is pressed, it connects the GPIO to voltage and triggers a high state on my Pi on my second floor, and when the button is let go, it would go back to a low state. Is there anyone out there who may have done this before?

Thanks

BMS Doug
Posts: 3824
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: Wireless GPIO

Wed Dec 09, 2015 8:34 am

433MHz transmitter / receiver pairs are pretty cheap.

433MHz wireless doorbells are commercially available.

the 433MHz doorbell transmits a coded burst signal, you can have your Pi learn the code and respond appropriately.

A coded burst is necessary as a simple pulse would cause nuisance triggering from radio noise (or other peoples doorbells or RF switches).

You could make your own 433MHz doorbell with a RF transmitter and an Arduino, another Pi or by finding a suitable chip that converts the bell push into a coded burst.
Doug.
Building Management Systems Engineer.

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KnightOfPi
Posts: 50
Joined: Sun Dec 28, 2014 12:57 pm
Location: Vienna - Austria
Contact: Website

Re: Wireless GPIO

Wed Dec 09, 2015 12:03 pm

Hi,

here is a tutorial for setting up a simple wifi data transmission without network:
http://www.knight-of-pi.org/using-pi-sw ... pberry-pi/

Pi-switch can be used to trigger remote power outlet sockets, too.

Have fun!
Check out www.knight-of-pi.org for many beginner-friendly tutorials!

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joan
Posts: 14748
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Wireless GPIO

Wed Dec 09, 2015 12:49 pm

KnightOfPi wrote:Hi,

here is a tutorial for setting up a simple wifi data transmission without network:
http://www.knight-of-pi.org/using-pi-sw ... pberry-pi/

Pi-switch can be used to trigger remote power outlet sockets, too.

Have fun!
Can those switches be controlled with keyfob type Manchester codes (e.g. 24 bit) or do they use a different protocol?

I have example code to capture/transmit (Manchester code format) keyfob codes for Python http://abyz.co.uk/rpi/pigpio/examples.h ... on__433_py and C http://abyz.co.uk/rpi/pigpio/examples.html#pdif2__433D.

SeaDoo4Life
Posts: 2
Joined: Tue Dec 08, 2015 11:45 pm

Re: Wireless GPIO

Wed Dec 09, 2015 4:49 pm

Wow, that's a lot more complication than I was expecting. I looked into the 433mhz tx/rx stuff, but it seems more complicated than what I wanted to deal with. Oh well, one more pi-in-the-sky idea relegated to the back of the pile.

pksato
Posts: 295
Joined: Fri Aug 03, 2012 5:25 pm
Location: Brazil

Re: Wireless GPIO

Wed Dec 09, 2015 5:08 pm

http://www.ebay.com/bhp/wireless-door-chime

With some modification on receiver, can be connect to raspberry pi.

stubright
Posts: 112
Joined: Sat Dec 24, 2011 11:12 pm

Re: Wireless GPIO

Wed Dec 09, 2015 5:21 pm

What about one of these, it's a wireless serial port with various IOT options, designed for raspberries.
https://www.wirelessthings.net/slice-of ... spberry-pi
with a key fob button
https://www.wirelessthings.net/iot-devices

Stu

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KnightOfPi
Posts: 50
Joined: Sun Dec 28, 2014 12:57 pm
Location: Vienna - Austria
Contact: Website

Re: Wireless GPIO

Wed Dec 09, 2015 5:35 pm

joan wrote:
KnightOfPi wrote:Hi,

I have example code to capture/transmit (Manchester code format) keyfob codes for Python http://abyz.co.uk/rpi/pigpio/examples.h ... on__433_py and C http://abyz.co.uk/rpi/pigpio/examples.html#pdif2__433D.
I'm not so deep into wifi, but here is a list of compatible devices:
https://code.google.com/p/rc-switch/wik ... ownDevices

Pi-switch is a fork of the arduino rc-switch library.
The Github
https://github.com/lexruee/pi-switch-python
has some more information...
Check out www.knight-of-pi.org for many beginner-friendly tutorials!

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joan
Posts: 14748
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Wireless GPIO

Wed Dec 09, 2015 6:08 pm

KnightOfPi wrote: ...
I'm not so deep into wifi, but here is a list of compatible devices:
https://code.google.com/p/rc-switch/wik ... ownDevices

Pi-switch is a fork of the arduino rc-switch library.
The Github
https://github.com/lexruee/pi-switch-python
has some more information...
Thanks. If I understand correctly the tristate codes are an extension to Manchester coding. I'll need to look a bit more deeply.

timrowledge
Posts: 1327
Joined: Mon Oct 29, 2012 8:12 pm
Location: Vancouver Island
Contact: Website

Re: Wireless GPIO

Thu Dec 10, 2015 5:23 am

There's a really simple example for the energenie basic RF controlled sockets as part of Scratch. As in *really* basic, but it turns them on and off which all they can do.

The product is https://energenie4u.co.uk/catalogue/product/ENER002-2PI and the code is here -
Energeni314.scrdrvr.zip
(1.39 KiB) Downloaded 31 times
and
energenie314-1.sb.zip
(42.89 KiB) Downloaded 29 times
All you need to do is run Scratch, unzip the screwdriver file and drop it on top of Scratch. That should load it and then just unzip the .sb file and load it in the usual way.
Making Smalltalk on ARM since 1986; making your Scratch better since 2012

pjcvdpol
Posts: 2
Joined: Fri Dec 11, 2015 3:58 pm

Re: Wireless GPIO

Fri Dec 11, 2015 4:06 pm

Hi,

I am hoping to find some help because I can't get the sender/receiver to work. I know they work because with two arduino's I get a perfect connection, the same when I push one of the buttons of the KAKU remote: I see the numbers on the serial monitor of the Arduino with the Receiver.

I have tried several how-to's / examples but none seem to work. I know the Pi is doing something, because when I connect a 5-3.3v level shifter between the datapin of the sender and the GPIO port of the Pi the LED of the levelshifter blinks when I do a ./codesend from the 433Utils toolbox.

Any ideas?

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