GPIO pin state changes be the "IF" in a trigger


I need to be able to monitor when a generator starts at a remote location. When the generator starts, be it automatically when there’s a power outage or when it tests itself, there is a pair of relay contacts on it that go hi/lo. I want that relay to act as a switch to set a GPIO hi or low and it will trigger an event such as send me a text (that the generator has started) it’s likely something simple but I don’t see it!!


suggestion: install a pullup resistor on the GPIO.
Cayenne doesn’t default pull a GPIO high,
and even though the relay opens/closes,
that doesn’t necessarily mean that the GPIO gets pulled low or high.
I experienced this exact thing.
A 1K -to- 10K resistor placed between 3v3 and the GPIO is needed.
I usually choose 2.2K because I have thousands of that value. :wink:
Do NOT connect the resistor to +5, it will burn out your GPIO.


You should also monitor engine RPM, current draw, voltage, temperature, oil pressure and fuel levels. -Just a suggestion.


Ok thanks for the reply! In the meantime I found the digital input I need for the trigger. Guess i was too impatient…lol looks like this will work well for me. I do have voltage sensors and I would like to have one on the generator starter battery. Also wouldn’t hurt to send signal of grid power loss, just to confirm actual power outage. Possibilities are endless!!


Funny you should mention this-
right now, I’m designing a dedicated PC board
specifically designed for remote generator monitoring and control.
I’m working on the tachometer input right now.
Trying to see if I can make a software tachometer,
programmed with Python.

The generator has enough unique requirements
that it warrants it’s own dedicated PC board design
-based on a Pi 3.

I build (er, past tense) off-grid estates- so, I definitely have a need…


So yeah I think already found it, but we have a digital input widget that you could use…then create a trigger to send a text message when the signal is HIGH/LOW. Were you able to figure it out? If not I can post a few screen shots. Let me know!

And also feel free to post your project to our ‘Projects Made With Cayenne’ category. There is also a project submission contest going :slight_smile:

See you around,