I have six DS18B20 (from the Brew Pi Store) where four of the probes read similarly (+/- 1°C) across a range from around 20°C up to 80°C. The other two share the characteristics as to the previous four in that they read similar temps, except they read around 4°C lower the the group of four.
Is there a mechanism available to correct the readings across all six so that the reading is uniform across all six? Would it be a simple as adding 4°C in code.
These probes will not be used with the Brew Pi but with a Arduino Mega in a similar application.
Which to trust, eh? You can calibrate the DS’s with ice water & boiling water, then in your code crank in whatever correction value you need to bring them in line with each other.
That sounds like a PITA, but if you’re geeky enough, it’ll be par for the course. Personally, I could live with the errors, as I’ve found that none of my store-bought thermometers (both electronic and old-school) were spot-on in agreement.
(I’d been all-grain brewing for 5 years before I discovered my dial thermometer was 8 degrees high, and still had great beer).