Indoor/Outdoor DS18B20's and a BMP180 trending


Making progress! Now have Indoor/Outdoor DS18B20’s and a BMP180 with trending pressure and trending outdoor temperature. Woohoo its a cozy 16F outside!



Trends are a little more interesting now that there is some data available. Check out that outside temp trend, down to 6F, dang.


Interesting indeed. There’s a dip on the inside temperature too…maybe you turn your heater off when you go to bed, and back on when you wake up?? I’d also be interested to see the weekly / monthly trend, once that data becomes available of course.

Cool stuff!



The thermostat is set to lower the temperature while we sleep and while we are gone during the day.

The trends really showed some swings today.

As requested here are photos of the sensors in the environment. Sadly, neither are very sexy installations. The outside one is mounted to my deck on the north side of the house where it doesn’t get any direct sunlight, and its dangling in open air so hopefully it’s obtaining the ambient temperature somewhat accurately. And both the inside sensors are either stuck in the breadboard (BMP180), or coiled up next to it (18B20).

Here is how I wired them up-



The family is growing. 3 RPi2b’s and a RPiZero all set up in Cayenne. Now all I need to do is hang some more sensors, actuators, indicators on this mess, wish me luck.

That poor Zero just doesn’t have the horsepower of his brethren.



Nice setup! I seem to be the poster child of bugs here lately, but hopefully I’ll get some of my ideas posted here soon too. Better to get the bugs out early though!


Don’t feel like the Lone Ranger. I’m putting together a bug report now, some of my triggers are generating errors and I don’t know why. And I thought my text message triggers were broken as well until I received a days worth in about a minute and a half, probably my carrier rat holing them.


^^Kinda looks like an Android (hint, hint)^^


I do have a couple questions for you.
How long is your wire for the outside DS18B20? I had read in the past that long wires can be problematic, just wanted to see what your experience is.
And regarding your ambient temp, I have noticed as well that if the temp sensor is in direct sunlight or touching something that is the reading will be way higher than it should be. Especially on cold days it will read up to 20 degrees warmer than what the weather channel reports. It’s also probably not very good for the insulation, I doubt it is rated for outside use.


Good morning Adam!

I’m guessing somewhere in the neighborhood of 20’ (6m). I’m using solid copper 2 pair phone line purchased from a lowes/home depot (don’t remember which). I did not have any problem at all with this length.

I intentionally put the ambient on the north side (shady side) of the house for this reason. And although not very pretty the reason it is dangling in the breeze is to try and isolate it from any other objects that may slow the reaction time of the sensor. If I were really cool it would be in one of those white boxes with louvers on the sides like the big weather stations.

We have a sensor at work (IIoT) that is mounted on the east side of a cabinet and every morning when the sun comes up it indicates a temperature that is way above ambient causing the heat trace to shut off prematurely, a real problem.

That’s a good point also, especially at my altitude, 4600’ (1400m), UV degradation is a real problem here. Fortunately all of my line is under the deck, so it should be good for a while.

Thanks for your interest,



Android coming!


Keep those bugs coming! Ha. We can’t fix them if we don’t know about them, so the whole Cayenne team over here appreciates it.



@bestes , Sorry, I just can’t sit idle while the iOS’ers get to have all the fun. I know your team is working hard on making this happen and I’m looking forward to a quality product when it is available. My Android jabs are good-natured and I’m smiling while I do it, keep up the good work!



Not to worry, I always love a good banter, and looking forward to more in the future!



Really got my geek on today-

Received a trigger text message from the outdoor 18B20 because it actually got above 50F here today. The text arrived while I was driving so the text to speech reader in my truck grabbed it and read the message to me.

For some reason it was very satisfying to have the message from the home front concerning what was going on in the backyard spoken to me while I was driving around.

It’s almost like I have a friend!



Just wait until it’s your car that is doing the actual driving.


Maybe this place really does suck.


Did you sensor get unplugged during that short time frame in the middle?



Not unplugged, just a glitch from the sensor. This RPi talks to a couple different IOT platforms and I see the same behavior on the others. I was trying to be funny showing that my world sucks to -22789 pascals. Which I think is pretty sucky, but I’m no pysisist.


This RPi has lost the indoor DS18B20. But gained a TSL2561, a PIR, and an IoT Power Relay which is a very nice micro controlled power outlet.

Power Switch Tail