Basic Moteino / GarageMote questions for a newbe

[JimSmith]

Hi, I'm a newbe and an oldbe.  I'm new to this whole Microcontroller world that I didn't even know existed until about a month ago.  I'm new to electronics other than measuring volts or testing for continuity around my car or on AC in the house.  Finally, the closest I'm come to a soldering iron is a propane torch for sweating copper pipes.  I don't guess I can use the torch much around a Moteino!

I'm also an oldbe since I learned assembler programming on a 24-bit CPU that was implemented across 12 chips, able to interact with a vast memory of 24K using 1K chips.  (If interested, google Four-Phase Systems, Lee Boysel and/or the Computer History Museum).  So while I've been around the block a few times, this is a new street I'm walking down.  Please go easy on me. 

That said, I've bought a book on electronics and have been trolling the internet when I discovered the Moteino and the different projects Felix has documented so well.  So, being an ambitious type guy, I want to implement the GarageMote as my first project. 

The issue is that my opener is a Genie screw drive (no chain), so I can't implement the hall effect sensors as described.  On the other hand, there already are travel-limit sensors (normally closed reed sensors?) that sense when the door is fully open or closed and stop the motor.  I want to use these sensors with my GarageMote.

There are 3 connections on the opener that are of interest: travel-limit open sensor, travel-limit closed sensor and common ground.  Each sensor has 2 wires: one connected to either open or closed; the other to the common ground.

With my meter I have determined:
•   Door closed: 0V between closed sensor/ground and 4.9 volts between open sensor/ground
•   Door open:  0V between open sensor/ground and 4.9V between closed sensor/ground
•   Door between fully open or closed:  4.9V between open sensor/ground and 4.9V between closed sensor/ground
•   A little less than 1mA (.96) on either 4.9V circuit

So it seems to me that when the voltage drops low, the opener knows the door is at the fully open or closed position and stops the motor.  When the voltage high on both sensors, the door is somewhere in between.

Now to my questions:
•   The GarageMote has 3 connections for each of the hall effect sensors.  How would I connect the 2-wire Genie sensors to the 3-wire GarageMote?  (My small understanding tells me I somehow need to connect to JP3 pins 3 and 4 for the open sensor and pins 6 and 7 for the closed.  This is probably wrong.)
•   I would also think (there I go again!) that I will need a resistors between the GarageMote and the 4.9V wires to reduce the voltage to around 3V or less.
•   I know I may need to alter the sketch, but I think that will be simple once the hardware is connected up correctly.  I will be able to do this on my own, but I just don't want to kill off a Moteino or two trying to learn what NOT to do.

Any input would be greatly appreciated.

Jim Smith
Dallas, TX
 

[Felix]

Hi Jim, welcome to the community.
I'm not too familiar with screw driven openers since I never had one and I think I very rarely saw one.
Anyway if you have a way to tap into the open/closed sensors then you're almost set. The 3 wires for each hall sensor are PWR (3.3V, GND, and INPUT from the sensor). So you'd have to use a resistor divider to cut down the ~5V signals from your open/closed sensors and plug those into the 2 INPUTS of the hall sensors. I think that's it. I can't remember off the top of my head what the sensor output is (HI/LOW?) when they are next to the magnet so you might have to tweak the sketch for the Moteino (ie flip the states of OPEN/CLOSED).
I recomment doing all of this on your desk using simulated conditions before you do the install. It's much easier and you can rapidly simulate a OPEN/CLOSE condition.

If you're very new to all this it might be a little challenging. I think the hardest part is to plow your way through the RaspberryPi install. My instructions are centered around a RaspberryPi install along with all the pieces that pertain to it (the NGINX web server, python, node.js etc).
Feel free to provide feedback and ask for help in here and we'll do the best we can to virtually assist.