Introduction: Gate Opener

The objective for this project was to create a gate opener that I can control the logic. I previously used a garage door opener and modified the circuits to accomodate an auto lock (prevents wind damage to the gate), light to aluminate the driveway when the gate is opening, an automatic closer if the gate is open and a IR proximity sensor to open the gate when people leave the property. The issue with the garage door opener is mainly the logic they have to monitor the amount to current drawn during the close cycle. In a normal situation, this is a safety feature to prevent the garage door from closing on an object. In my gate project, the electric ram I use will draw more than the opener liked during cold weather and would not close.


LiftMaster 850LM

Various remotes and keypad for the 850LM

Project bread board, project board etc.

(3) 10k resistors

8 pin terminal block(s)

(1) two relay board

(1) uno board, various wires

Step 1: Logistics

You need to add two switches to the gate that are used to determine the state of the gate. I used two because the auto-close logic was added later. If I find time, I'll remove one of the switches to clean it up a bit. I used magnetic NO as they are exposed to the weather. I ran cat6 cable from the proximity sensor to the board and switches. Attach the wires keeping track of the color codes for later assembly.

Step 2: Code

Attached is the arduino code I used, here are a few items I tripped across:

- my gate takes 16 seconds to open and I used an 18 second time to allow full operation in high winds or pushing snow along the ground level.

- I used 60 seconds for the auto-close timer, adjust as you see fit. In testing.

- I found noise on my analog inputs and had to add a resistor to ground to help. I also used the value of 1000 to determine if the analog input was 'on', if you have cleaner signals adjust this as you see fit.

- The relay board I used needs a low signal by default to close the contacts. If your relay coil wants power, flip the LOW to HIGH on that logic above.

Step 3: Enclosure

I created a very crude enclosure to mount the uno board to and used double sided tape for the project board and relay board. I have the assembly in an enclosure so I did not need to consider weather proofing. If you notice in the photos, I soldered wires to the project board with care to ensure I can disassemble the pieces later without issue. I tend to continue to make changes and like to make it serviceable down the road without having to unsolder wires and lose track of what goes where. I think the terminal blocks were $10 for 60 pieces, I like to use these but can obviously be omitted.

This logic functions as many commercial gate closures and has no utilities to prevent closing the gate on an object, car, or person. I would not use this in a residential application.

Step 4: Crude Schematic

I did not find an Uno drawing in the digikey tool and used the best one I could find. The pin layout is incorrect for the board, however the pin labels work for this purpose.