The DS18B20 (on a Feather Huzzah) seems to miss some rapid changes that the SHT30 (on a D1 mini shield) reports, even though TelePeriod=60 for both. The DS18B20 does seem to report changes within 60s of each other sometimes so I think we’re just seeing duplicate values elided, which I do expect.
The thermostat on the wall near them (which they’ll be replacing) reports 70F, closer to the DS18B20. I have a thermocouple for my Fluke multimeter which I may try to calibrate in ice water and then use to calibrate the temp sensors, though I’m curious if there’s an easier way; or I might not bother since I care more about just setting the climate for room comfort than specific numeric temperatures.
The data path is: Tasmota -> MQTT (Mosquitto) -> HomeAssistant -> InfluxDb. In this case the chart’s just in InfluxDb’s data explorer, though I have some dashboards in Grafana too (which was the motivation for having Influxdb).
If you have a multimeter that can do 4 wire temp measurements, a PT100 is probably the most precise a consumer can get at room temp. It automatically compensates for wire resistance and such. Standard for measuring temperatures in a smaller range than a thermocouple and doesn’t need as much amplification.
The problem is that there is not a certainty that the SHT and DS18 are just wrong by offset. Looking at your graph there is quite some unstable measurement accuracy in one or both of them too. The top line has many sustained spikes that the bottom doesn’t, for example.