Background radiation measures are typically of very low values and given the stochastic nature of radiation (see graph on previous post), it takes some minutes to achieve a correct cumulative medium value, so a clock counter is needed.
I slightly modified the program to add an incremental clock on the lower right of the LCD: the clock shows up for the first 2 minutes and a half, which is the minimum time for a measure. From there on to five minutes, the clock alternates every ten seconds with the corresponding accumulated uSv/h value for the CPM (counts per minute). From 5 minutes on the clock is not showed anymore, just the accumulated uSv/h value, and a vertical bar appears on the middle of the second LCD line to indicate that the five minutes mark has been passed.
Here is the complete code: radiation_shield_buffer.ino
Also as git repository here.
Also, the different units for radiation measure are very confusing and some of then, now deprecated, are found on textbooks and articles… So I stuck a little table to my carton box, with fast conversion factors.
Human exposure to natural background radiation,
2.4 mSv/a = 0.27 μSv/h avg
0.081 μSv/h = 0.72 mSv/a ~ 10 CMP
0.154 μSv/h = 1.36 mSv/a ~ 19 CMP
0.162 μSv/h = 1.44 mSv/a ~ 20 CMP
0.244 μSv/h = 2.17 mSv/a ~ 30 CMP
0.27 μSv/h = 2.4 mSv/a ~ 33.2 CMP <—-
0.325 μSv/h = 2.88 mSv/a ~ 40 CMP
0.406 μSv/h = 3.61 mSv/a ~ 50 CMP
114.1 μSv/h = 1 Sv/a
1000 μSv/h = 8.766 Sv/a
Oh, and added a power switch, so now the detector is almost perfetc.