Garage Door Tilt Sensor

I need to make a few battery operated garage door tilt sensors.

Are there any considerations on which sensor to choose? I think the new 9-axis sensor could do it, but may be bad on battery life due to idle power usage.

Or I suppose I could just do a contact switch, but I have had bad luck over time with every switch based tilt sensor I’ve made, that is why I was thinking about doing something fully digital. But I guess I need to think through this some more.

The RAK1904 won’t consume much current while active. Check this link. You can probably enable it’s interrupt functions which can wake up the MCU on WisBlock Core once threshold is detected.

That is what I was thinking, and then one can tell orientation (open/close) looking at the acceleration value on whichever axis is in the plane of gravity.

I ordered 2 RAK1904, so I’ll try it out in a few weeks when they get here.

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A number of modern garage door opener systems support connecting over Wifi. Check out the “MyQ” applications to trigger such things.

Using their app it allows you to determine the status of the garage door system , and allows you to integrate to Amazon drop off services, and remote control from the app.

I haven’t found a way to integrate it to GOogle Assistant or Google Home just yet - this portion of the product seems a bit “rickety”, but it’s pretty likely that a Chamberlain, or other garage door opener purchased in the last 15 years has a similar capability to connect to wifi – check it closely !!

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With regards to Google Assistant for voice command, my colleague created a tutorial on using WisBlock Core RAK11200 and IFTTT :+1:

That’s a good point.

That said, I explicitly do not want to control my garage doors remotely. I just want status indication.

I currently have a few Z-Wave tilt sensors, but as all of those are metal ball switches for the indication, and tend to get stuck or unreliable after many years (or extreme temperatures), I thought I would try a more solid state approach.

Well, the good news is that it is quite easy to do this with the RAK1904… If using timed polling.

Bad news is that I can’t get the interrupt handlers to work properly at all. Tried at least 50 different combinations/settings, and either I get no interrupts, or I constantly get interrupts even though nothing is changing.

I’m sure it is something I’m doing wrong, but it will have to wait for another day when I have more energy.

Never mind, I think I got it now. Seems like that happens every time I give up and post that I “can’t get it”. :slight_smile:

Needed to make the interrupt not latched on the LIS3DH.

And if running on battery, turning off the pullup resistor on the sensor is of critical importance (by approximately 140 uA)… Went from 177 uA average to 36 uA.

Putting it in low power mode doesn’t change the power usage much at the frequencies I’m using (maybe 6 uA), but turning off the resistor definitely does.

Should probably put that little tip in the datasheet. :slight_smile:

Thanks for the tip (once again!) @beegee . I knew about low power mode, but didn’t realize you could turn off the resistor (it is in the ST manual for the sensor, but it didn’t jump out at me).