Mortimer wrote: ↑Fri Jul 27, 2018 3:54 pmAh but all of that relates to the accuracy of the real time clock circuit.
1. "+/-2ppm from 0 to 40degC" RTC is better than 2ppm.
It says nothing about the accuracy of the temperature sensor.
2. +/-2degC temperature accuracy is more like it. Your temperature readings covered a range of 4degC, which tallies with the claimed accuracy doesn't it?
3. temperature sensor to measure the internal temperature of the RTC chip
not to measure ambient air temperature.
4. To be fair it won't be far out, need to compensate for the internal chip temp.
Thanks for the clarification. I have not been bothering much about the difference between RTC's time output and temperature sensor temperature output.
Of course time and temperature are completely different things. I casually mixed them altogether and therefore made a big confusion.
So I needed to do some measurements to clarify my mind. I first collected 6 digital thermometers and read them at steady room temperature, with air conditioner switched on for about 1 hr, and no electric fan air flowing around. The readings are show below.
I will from now on use the first 2 meters as bench mark (actually I am not sure if I can use this term) standards for the following RTC experiments. They differ between themselves by about 0.2 Centigrade degrees, and from the average of 6 meters by 0.3 C degrees max. With this rough idea of
Ah, I think I also mixed the terms accuracy and tolerance. The meters should have an accuracy of 1 decimal place or 0.1 Centigrade degree, and a tolerance of about 3 Centigrade degrees max.