Dear all, I noticed that the temperature measurements are delayed by a lot because of the way the sensor is packaged. I understand that measuring sudden temperature changes reliably may not be the primary use case, but then there isn’t really a point in sending a signal multiple times a second.
I did the following test:
- I noted the starting temperature of the tag when it was left on the table, it was about 21 degrees.
- I held the tag in both my hands, probably my hands are about 36 degrees.
- I waited till I got the first measurement above 30 degrees
- I put the tag back on the table
- I waited till the first measurement below 25.5 degrees ((30 + 21) / 2).
This gives me 2 time deltas: t_warm time from step 1 to step 3, and t_cold, time from step 3 to step 5.
I did these tests with:
- the ruuviTag in his original case, closed.
- the ruuviTag with the upper part of the case removed.
- a DS18B20 waterproof sensor attached to my raspberry pi.
the ruuviTag in his case needs more than 3 minutes to become warm!!! and after I put it back on the table it is still getting warmer for 1 minute!
In comparison the DS18B20 sensor needs 28 seconds to become warm.
With the open case things get a bit better, the sensor gets warm in less than 2 minutes.
Here are the (very inaccurate) measurements I made:
device, t_warm, t_cold
ruuvi_closed_case, > 3 min, > 6 min
ruuvi_open_case, ~ 2 min, > 3 min
DS18B20, 28 sec, 2 min and 21 secs
I guess the plastic case is isolating the sensor a bit too much.