Hi folks,
I've done a bit of searching and not quite found answer that fits.
I have a solar pool heater that pumps water to solar heating panels on my roof. The controller that comes with it is a simple device that measures the pool temp, measures the roof temp, then turns on the pump if a gain is to be made.
I want to read these two temps from the unit and publish them to my home automation server. I'm looking to watch how weather affects the temp drop in the pool over spring, see if there are some better economies to be found.
The sensor near the pump seems to be similar to a db18s20, I'm yet to confirm this or the roof sensor. The plugs connecting the sensors to the unit make it an easy mod...
Can I piggy back onto these sensors and take my own readings? I'm looking at connecting them to some esp8266 boards and sending the temps over MQTT.
Am I crazy? I know I could try to tap in my own temp sensor near the pump, but the one to the roof is going to be awkward at best...
Let me know, thanks heaps!
I keep a watch on the basement temperature using a browser and a little HTML magic:
https://www.hackster.io/rayburne/nodemcu-esp8266-remote-temperature-using-websockets-5956c4
You could simplify, drop the javascript, and MQTT it...
You could IMO only piggyback if the sensors were analog output, but the ESP8266 is a 1 Volt AD, so it is likely that you would need a voltage divider which would "load" the sensors and have an unknown effect on the existing controller and its readings. My proposal is to use new, separate temperature sensors. I have never heard of anyone being successful at piggybacking I2C or SPI although there are some crafty folks out there.... but, I would say it is best not attempted!
Many folks poo-poo thermistors, but if you use 1% (or better!) resistors and a decent Vishay thermistor then you are going to get 1C accuracy.
Ray
brendanheyu:
seems to be similar to a db18s20, I'm yet to confirm this
Similar isn't enough, it either is a DS18B20 or it isn't. It 's probably simpler not to bother confirming anything, and use your own.