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Friday, September 13, 2019

Time to recalibrate?

Since I added the 5v external power supply on the Sensor Modules, it has had an effect on the readings of the sensors. The system looks at historical data to determine the soil moisture as a percentage. If the highest value ever read on a sensor in a pot with dirt was say 800 and the lowest was 200, then rather than calculating the moisture level as a percentage from 0-1023 we would calculate it as a percentage from 200-800. So if the reading on the sensor was 400, that would be roughly 40% if calculated between 0 and 1023, but if you calculate it between 200-800, then 400 is actually about  33%.  With the new external power supply, this could affect the readings, so the sensors should have been re-calibrated to find their values in dry air, and sitting in a glass of water, as this will affect the final calculated value, or percentage.

Here is what I'm seeing now on the web page showing the Grow Room Overview, this is only the Flower section.


There are two plots which are pegged at 100% and have been since they were last watered. It seems the readings now are higher than before, so it will be a while before it sinks below the calibrated WET value, and continue to report 100%. 

Re-calibration involves pulling the sensor out of the pot, touching a button on my phone to calibrate the value in dry air, then putting the sensor in a glass of water, and touching another button. Pretty simple actually, assuming you have easy access to the sensors :)

Also, the estimates of time till next watering are way off, and in some instance, non-existent, they are also based on historical data.


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