A great option for adding temperature and humidity (and dew point) measurement to the Arduino (and freeduino) is to use the Hurimel HS sensor. It is packages as a small board, approximately ″ x 2″ with 4 screw terminals.
The only electrical connections are these 4 – for ground, and I/O pins used on the Arduino – analog and 2 digital. The pin references used in this article are taken from a Freeduino BBB board.
The 4 pins on the Hurimel are THERM, PULSE, GND and V+. Besides a connection to ground on the Arduino, additional pins will be required – an analog and 2 digital pins. One digital pin is used to provide power (+5VDC), in this example, pin 2 is connected to the V+ screw terminal on the Hurimel. Digital pin 5 can be used to count the pulses, connected to the PULSE screw terminal on the Hurimel. Finally an analog input is required for the temperature reading. Analog pin A5 on the Arduino connected to the THERM screw terminal on the Hurimel. Note that a k resistor must also be placed between 5V and analog pin A5 on the Arduino.
In summary, the electrical connections in this example are:
Arduino BBB digital pin 2 – Hurimel V+ screw terminal
digital pin 5 – Hurimel PULSE terminal.
GND pin/connection – Hurimel GND terminal.
Arduino BBB analog pin A5 – Hurimel THERM terminal.
analog pin A5 – k resistor – Arduino BBB GND +5v DC pin/connection
In a future article, the Arduino source code required to read the temperature, humidity and dew point measurements will be discussed.
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