Newbie: How should I open our garage door?

koal

Hi there.

I’m totally new to Raspberry Pi’s and thus of course new to pimatic, homeduino and so on. I thought about buying a pi during the last months, but never knew what to really use it for.
A few days ago our keypad lock for the garage door stopped working. This should be my first thing to do with a pi.
So all the pi should do is close a circuit; of course inside, not outside like the keypad lock. Users (familiy-members) should connect to some web-interface with their mobile using our wifi and push a button to open/close the door.

So before even owning a pi (the postman should make me happy with 2 pi’s within the next 2 days) I went to buy a printrelay (HF3FA). At that moment I thought I could switch one of the 5V-pins of the pi on/off. Now I know better. As far as I unterstand, I would have to use a transistor triggered by a 3.3V GPIO to close the circuit powered by 5V containing my relais to close the circuit from the motor for the door…
Or would it be possible to only use a transistor to close the circuit for the motor (as far as I recall it is 12V or 24V DC)?

I’m a software developer but not really into electronics; so this sounds complicated for me when I think of resistances and so on.
Meanwhile I found out about pilight and finally pimatic. Would it be possible - or rather would it make sense - to open the door with a 433MHz-Transmitter using homeduino (the motor of course has a 433 receiver for transmitters in our cars; though at the moment I’m not really sure if it is 433…)?? Or using pimatic and some relay-board? But which? If using a relay-board, is there a switch-type like a push-button? Or would I have to use a rule for switching this GPIO to off when on for let’s say 1 second?

Another nice solution (but very expensive I think) would be a finger-print solution instead of the keypad lock. Which would only replace the web-interface accessed via wifi; the relais-vs-433 question would not be answered…

Now some more general questions.
If using a nano (sooner or later I’m sure I will), how do I know which one to buy? Amazon/Ebay/Aliexpress is full of differnt offers…
If using homeduino with a 3400 RF kit (which seems to be the best concerning to this forum), am I still able to use the remaining GPIOs from the nano and pi for other purposes??

What would you recommend me to do?
What solution would you implement in your own home??
The 433-solution would maybe have the advantage that the pi wouldn’t have to be in the garage, as the garage is part of the basement having the living room right above. So the pi probably could be in the living room and do more useful things in the future…

Sorry for this very long text. But I’m so excited. I love it when an old man can be a child again

Best regards,
Koal

leader21

First of all welcome to the wunderful world of Pimatic
I cannot answer all of your questions but hope to give information.
Guess there will be other users who will give their 2 cents too.

@koal said:

Users (familiy-members) should connect to some web-interface with their mobile using our wifi and push a button to open/close the door

Pimatic is offering a nice plain gui as you already have investigated. You can add users and assign roles. At the following example you can see an admin and a resident. the admin has all rights and the resident only to control devices (for switching devices eg.) :

    {
      "username": "admin",
      "password": "secret",
      "role": "admin"
    },
    {
      "username": "chris",
      "password": "secret",
      "role": "resident"
    }
  ],
  "roles": [
    {
      "name": "admin",
      "permissions": {
        "pages": "write",
        "rules": "write",
        "variables": "write",
        "messages": "write",
        "events": "write",
        "devices": "write",
        "groups": "write",
        "plugins": "write",
        "updates": "write",
        "controlDevices": true,
        "config": "write",
        "restart": true
      }
    },
    {
      "name": "resident",
      "permissions": {
        "pages": "read",
        "rules": "read",
        "variables": "read",
        "messages": "read",
        "events": "read",
        "devices": "none",
        "groups": "none",
        "plugins": "none",
        "updates": "none",
        "controlDevices": true,
        "restart": false
      }
    }
  ]

I went to buy a printrelay

There are already assembled relay pcb like that on ebay

I’m a software developer but not really into electronics

nice to hear. want to contribute in developing Pimatic

would it make sense - to open the door with a 433MHz-Transmitter using homeduino (the motor of course has a 433 receiver for transmitters in our cars; though at the moment I’m not really sure if it is 433…)?? Or using pimatic and some relay-board? But which? If using a relay-board, is there a switch-type like a push-button? Or would I have to use a rule for switching this GPIO to off when on for let’s say 1 second?

Ok first of all if using homeduino and 433 MHz transmitting, it would be neccesary to maybe develop a new protocol for the garage door. usually these RF protocols are secured via rolling code and not that easy do reverse engineer. I remember that @icesory and @willy already tried to implement roling codes.

Another nice solution (but very expensive I think) would be a finger-print solution instead of the keypad lock. Which would only replace the web-interface accessed via wifi; the relais-vs-433 question would not be answered…

Nice idea. Again have a look at ebay Could be an option and
Cannot tell you about the complexity of programming but i guess it would be possible.
can imagine it could look something like that when ready build https://www.youtube.com/watch?v=z-LW33ILyxw

If using a nano how do I know which one to buy? Amazon/Ebay/Aliexpress is full of differnt offers…

you do not have to buy the original arduinos. the clones are fine! take a nano with CH340 chipset. you can also go for an uno or mega, doesn’t matter where to buy. If you need more I/Os take the mega.
but as said - chipset CH340, since the FTDI chips caused some trouble in the past.

If using homeduino with a 3400 RF kit (which seems to be the best concerning to this forum), am I still able to use the remaining GPIOs from the nano and pi for other purposes??

Go for the 3400 RF! You won’t regret
And yes, you are still able to use all remaining GPIOs.

The 433-solution would maybe have the advantage that the pi wouldn’t have to be in the garage, as the garage is part of the basement having the living room right above. So the pi probably could be in the living room and do more useful things in the future…

There’s nothing more useful for a Pi than serving Pimatic
I’m having three Pi’s operating at my house, one exclusively for Pimatic.

the garage installation would have the advantage to have all connected hardware directly at one place. You can go for a keypad and add it with homeduino for example. Never done this before but homeduino seems to offer that possibility https://github.com/pimatic/homeduino/tree/master/libraries/Keypad Then you could use some rules to operate the relay.
Another option for the acces control would be a RF ID solution. Maybe that is the better way instead of a keypad?

Sorry for this very long text. But I’m so excited. I love it when an old man can be a child again

Wish you very much fun with pimatic now and in future
I haven’t had the answers you expected but maybe some things to consider.

incmve

RF is limited in range and walls and ceilings limit the range even further, but the hardware on ebay is cheap and it’s always handy to have RF on your Pi
If the RF doesn’t work or the protocol can’t be reversed engineered have a look at the an ESP8266+relay

koal

Hey guys.

Thanks for your answers…

Meanwhile I looked up the type of the garage door operator; it’s a Chamberlain Liftmaster PRO 8000. It doesn’t support 433MHz, it receives at 27MHz.
So the 3400 RF is no solution (though there is one on the way for playing around a bit ). I also ordered a nano-clone and some pre-assembled relay pcb’s.
The ESP8266 sounds like a nice solution, but for now I’ll try to solve it directly from the raspi/nano with a relay.

As far as I learned by now, the GPIOs from the pi work on 3.3V; so I would have to use some transistor and resistors to switch the relay.
I could not find out if the GPIOs from the nano work on 3.3V or 5V, so I could directly switch the relay…

beikeland

Nano comes in both 3.3v and 5v versions. BUT the pins can only handle about 40mA.

HOWEVER, the relay will induce a high voltage as a result of back emf when disengaging and you need a diode to short this. You’ll also likely need a transistor to switch the relay as the current handling of the pins will likely be insufficient.

sparkfun has a nice breadboard layout of how to connect up transistor, diode and relay.

koffienl

@beikeland said:

Nano comes in both 3.3v and 5v versions. BUT the pins can only handle about 40mA.

HOWEVER, the relay will induce a high voltage as a result of back emf when disengaging and you need a diode to short this. You’ll also likely need a transistor to switch the relay as the current handling of the pins will likely be insufficient.

sparkfun has a nice breadboard layout of how to connect up transistor, diode and relay.

I don’t think that you need to worry about that for a Nano. All you have to do is toggle some relays to get the device operating. That won’t use that much power/amp from the Nano.
(aaah … the link you provided was for buidling a relay from scratch. The OP ordered a relay ready for pi/nano)

@koal Can you post a link to the pcb/relay you have ? I don’t think the 3.3v / 5v difference is a problem for the relay.

Pimagical

@koal a chamberlain upgrade to 433mhz could be a option check for more at http://www.garage-door-remotes.co.uk/chamberlain.htm or using a cheap kaku impulse switch http://eye-vision.homeip.net/6022/garagedeur-openen-met-je-smartphone/