I wound up doing my own opener with an ESP8266 and a relay.
I can tell you that closing the relay for 75ms seems to work to trip the light. The following is my Arduino code that loops a buzzer beeping & flashes the light a few times. The flashing light is noticeable with the clicking of the relay.
for (i = 0; i <15; i++)
{
digitalWrite(13, LOW); // GPIO13 Closes Garage Relay
digitalWrite (buzzer, LOW) ; // Turn buzzer ON
delay (75) ; // Delay 75ms for Garage Light
digitalWrite(13, HIGH);
digitalWrite (buzzer, HIGH) ;// turn buzzer OFF
delay (150) ; // Delay 150ms
}
I came to the same conclusion by reverse engineering the hardware of the wall button. Additionally there’s a RF remote lock-out feature with a different pulse duration.
I hesitate to use this in the official firmware, because short pulse might have different effect with different types of openers and there is no feedback for the remote operator to know the current state. I’ll consider adding this ans an optional feature.
Great info! It is interesting. Not sure that being able to enable the remote RF lockout has a lot of applications but maybe someone has one. I think figuring out a way to flash the light before closing by just changing the firmware could obviously be very useful. Thanks for your continued work!