Week 20

 Tested sensors connection to NodeMCU ESP8266

DHT 22 sensor to detect temperature, humidity and heat index

For the third week on semester 3,  I have installed all the library needed for ESP8266, then I add DHT 22 sensor to connect to the microcontroller. The DHT22 is an essential digital temperature, heat index and humidity sensor that needs minimal effort to install. It employs a thermistor and a humidity meter to quantify the ambient air and outputs a digital signal on the information pin. DHT 22 is somewhat more accurate and has a somewhat wider range. It is straightforward to use, however data gathering requires patience. After a while, the sensor works well and manage to issue the reading.

Soil moisture sensor to sense the moisture of soil in field.

Once the DHT 22 are stable and able to read out the data. I insert another sensor that I believe is a great sensor to help this agriculture monitoring system, which are the soil moisture sensor. The fork-shaped probe, which has two exposed conductors, functions as a variable resistor (similar to a potentiometer) whose resistance fluctuates with the volume of water in the soil. This resistance is inversely related to soil moisture, which implies that the more water in the soil, the greater the conductivity and the lower the resistance. Following that, the less moisture in the soil, the poorer the permeability and, as a result, the larger the resistance. Based on the impedance, the sensor produces a voltage output, which we can measure to determine the moisture level.