Finished experiment 1.

calibration_and_testing/exp01_sensor_calibration.md

@@ -16,28 +16,40 @@ necessary to adjust the user experience of the final device.
 
 ## Methodology
 
-1. Prepare the code. Three versions of the code will be used raw, slightly
+1. Prepare the sensor. The power input should come from the 5V output of the
+   board. This is important since different voltage inputs to the sensor will
+   alter the obtained measurements for an identical humidity.
+2. Prepare the code. Three versions of the code will be used raw, slightly
    smoothed and heavily smoothed.
     - Raw version outputs the sensor's measurement to the serial port in
       real-time, unfiltered.
     - The slightly smoothed version will take 10 measurements with 50ms of
       delay between each and return the mean.
-    - The heaviliy smoothe version will take 100 measurements with 50ms of
+    - The heavily smoothe version will take 100 measurements with 50ms of delay
-      delay between each and return the mean.
+      between each and return the mean.
-2. Prepare the soil
+3. Prepare the soil
     - In a small recipient (weight: 80g), place 200g of soil.
     - Let it dry for X days (collection on 24/10/2022) to obtain the driest
       possible soil.
-3. The next steps will be performed repeteadly by adding 10ml of water to the
+4. The next steps will be performed repeteadly by adding 10ml of water to the
    soil at each step. Start by first measuring the completely dry-soil. Ensure
    that the water is distributed uniformly across the soil. For each amount of
    water up to a max of 200ml, and for each version of the code:
     - Obtain measurements from the sensor. If the measurement is unstable,
       record the observed range and the most frequent value.
-4. Finally, obtain measurements in a glass of pure water, with no soil at all.
+5. Finally, obtain measurements in a glass of pure water, with no soil at all.
 
 ## Results
 
-Make line chart with measurement by hydration level.
+See file `exp01_sensor_calibration.ods`.
 
-## Conclusions
+## Conclusions
+
+The results where a bit dissapointing. The sensor signal was clearly moving
+when the dry soil received the first 10ml of water. But, from that point on,
+the next additions of water barely modified the returned signal. Eventually,
+there was no significant change in the sensor values. This is showing a
+sensitivity way below what I was expecting.
+
+I have been reading about some modifications in the circuit to improve the
+accuracy of the sensor. I'll design another experiment to try them out.

calibration_and_testing/exp02_sensor_calibration_with_aref.md

@@ -0,0 +1 @@
+https://makersportal.com/blog/2020/5/26/capacitive-soil-moisture-calibration-with-arduino

requirements.md

@@ -20,8 +20,8 @@ way possible._
 - The device operates with one or two 9V batteries.
 - The device comes with a QR code linking to the minimal instructions for setup
   and operation.
-- Reading-time not accounted for, the device can be installed in under a
+- Documentation reading time not accounted for, the device can be installed in
-  minute.
+  under a minute.
 
 ## Operation acceptance criteria
 
@@ -29,4 +29,5 @@ way possible._
   doable without any sort of equipment.
 - The device can run for at least 6-months without a battery change (assuming
   the starting point is two fully loaded 9V batteries).
+- The device can be turned off and on without any special equipment.
 -