EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by rjsears on Wed, 13/04/2016 - 06:59

I have a bunch of EmonTHs with the DS18B20 in the DHT22 socket and I want to add multiple external DS18B20s as well.

I can find sketches for a DS18B20 in the DHT22 socket and I can find sketches for multiple external DS18B20s, but not a sketch that combines both.

Does something like that exist? I am not a programmer, so my feeble attempts to mash the two together never made it past the compiling stage.

Thanks

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by Robert Wall on Wed, 13/04/2016 - 23:50.

Why do you think you need to use DS18B20s in both places? How many do you need, and how are they wired (star or in-line)?

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by rjsears on Thu, 14/04/2016 - 00:44.

Hi Robert -

I need three temp sensors on one particular emonTH. I have an onboard DS18B20 sensor already installed in the DHT22 socket (ordered from OEM this way) and I have two external DS18B20s connected via the terminal block (both of them connected directly to the terminal block) in a star configuration.

I guess I could just add a third external DS18B20 to the emonTH but I was hoping to use the temp sensor already onboard.

I have one sketch that recognizes the DS18B20 in the DHT22 socket as well as a sketch that allows me to see multiple external DS18B20s, but I cannot get a sketch to work that does both, and that was what I was looking for on this particular emonTH.

I was just wondering if someone already had a sketch to do that....

Thanks (again) :-)

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by Robert Wall on Thu, 14/04/2016 - 08:58.

I don't know of a sketch, but it should not be difficult to combine the two. But by far the easiest solution - as you can't successfully do the sketch - would be to add the third sensor to the terminal block.

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by pb66 on Thu, 14/04/2016 - 11:57.

Could you not just bridge the on-board temp data pin and the external temp data pin on the emonTH and use the multiple external sketch with the on-board code looking to an unused pin so it thinks there is no on-board sensor and 3 external despite the physical location?

Adding a short piece of wire and changing a pin number might be an easy enough route.

Paul

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by rjsears on Sat, 16/04/2016 - 08:52.

Well, it is not as pretty as some code out there, but I finally managed to get a sketch working with two external DS1820B sensor and another DS1820B in the DHT22 socket.

Since I am not a programmer, this took a long time for me to figure out, but it was fin and in the end, it works great.

I have the serial set to 38400 because for some reason below that I get partial garbage out of the IDE. Just a line or two, but still annoying. I also have it set for (°F) as I am in the US.

Maybe this will help someone else out there!

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by Robert Wall on Sat, 16/04/2016 - 12:00.

You probably needed 38400 Baud because the serial output didn't complete in time - it's interrupt-driven and if another interrupt comes along, the timing goes awry. Adding a small delay after the offending "Serial.print" usually does the trick.

Re: EmonTH w/Multiple external DS18B20 AND DS18B20 in DHT22 socket Sketch

Submitted by rjsears on Sun, 17/04/2016 - 06:32.

Thanks Robert -

Adjusting the delay will give me some tinkering to do!

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