GateControl

ESP8266 firmware that implements a garage gate controller.

Physical setup

You'll need:

• a garage gate equipped with a motor
• one sensor each at the top and bottom end positions to locate the gate
• a light barrier
• WiFi, MQTT
• a signal light with which you warn people before automatically closing the gate.

NodeRED

For GUI and for controlling the signal light, I use NodeRED. Here's the flow:

The main part of the setup is the CPU node. Its state machine can be admired here:

Status indication

The controller regularly publishes the current state of the gate on the ctrl/<ChipID>/current_hard_position MQTT topic. You can (and should) use this information to drive a signal light, or monitor for the ERROR state.

I'm using a LIFX light bulb for the signal light:

Controller State Machine

The controller's state machine is focused on providing all the features in a safe way. That means, whatever weird situation we're faced with, the objective is to never make it worse. This is achieved by inserting yield points into the state machine, where external commands are necessary to continue. If such a command arrives, we can safely assume that warnings are taken care of. Otherwise, we cannot know what's going on, so we have to abort and return to a safe state.

Autoclosing

When you want to leave the garage, having to close the gate manually can be a nuisance. Thus the controller supports autoclose, through a separate physical button connected to one of the inputs. The controller then monitors the light barrier, and if it was clear for a while, automatically closes the gate. Again, using the status indications published on ctrl/<ChipID>/autoclose to drive a signal light is highly encouraged.

Remote closing

To command the controller to close the gate:

• send an MQTT message of CLOSED to ctrl/<ChipID>/set_hard_position.
• If the controller accepted the command, it acknowledges by sending waiting to the ctrl/<ChipID>/close_ack topic.
• You should now trigger the signal light to show a warning that indicates clearly that the gate is about to move.
• 10 seconds (± some wiggle room) after you sent the initial CLOSED command, send COMMIT to ctrl/<ChipID>/set_hard_position.
• If the controller is satisfied with your timing, it replies with commit on ctrl/<ChipID>/close_ack.
• The controller triggers the gate to start moving and sends closing on ctrl/<ChipID>/close_ack.

This scheme basically implements two-phase commit. It is meant to ensure that when individual components fail (like the signal light being unavailable or NodeRED being restarted), the gate does not start moving unexpectedly.

ESP Pinout

Here's how things need to be connected to the ESP. Comments indicate glitches and caveats, most of which are to do with earlier versions of my PCB being less than ideal. I'll probably need to re-do mine so that I can fix these.

All inputs need to be pulled low when they are active, and high otherwise.

Input	Pin	Output	Comment
Sensor Monitor	D0		not yet implemented
Sensor Up	D1		needs external pull-up
Sensor Down	D2		needs external pull-up
Autoclose button	D3		must not be pulled low during boot
	D4	Error LED	ESP on-board LED, LOW = on
	D5	Gate Trigger	HIGH = on
Lightbarrier blocked	D6
Lightbarrier clear	D7
	D8	Status LED	HIGH = on

Note that while it would probably be better to drive the Status LED and the trigger relay by pulling their pins LOW, we can't really do that since that would incur quirky boot behavior. We really do not want the gate to start moving uncontrollably whenever the ESP is reset, and those pins are pulled LOW during boot, so LOW must mean "off".

Also note that I'm thinking about re-using the Status LED to also drive a relay to enable the Light Barrier only when needed. In that case its behavior would change, because blinking would be a really bad idea (or I'd need to debounce that in the hardware, ugh).

LEDs

• Error LED: Blinks while connecting to WiFi, off while running, static when error
• Status LED: Static when autoclose enabled, blinks when about to close

Disclaimer

I broke my gate once during this project, and it's somewhat probable that so will you. I'm obviously not liable for any damages you cause using this project.