“A thermometer and humidity display that shows the current temperature, temperature index (feel), humidity level and dew point.
For this project we are building an Arduino-based thermometer and humidity display. It shows the current temperature, temperature index (feel), humidity level and dew point. It also displays a graph of the readings from the past 12 hours.
If you plan to 3D print the case included with this project, you will need the exact components listed below. If you use alternative components they may not fit inside the case.
You will need:
Arduino Uno R3 (or compatible board)
Adafruit Proto-Screwshield (Wingshield)
Velleman VMA412 2.8” Touchscreen Display Module
DFROBOT DHT22 (SEN0137) Temperature and Humidity Sensor (a DFROBOT DHT11 (DFR0067) sensor can be used instead with a minor code change)
Panel Mount 2.1mm DC barrel jack - The barrel should be ~11.5mm in diameter and ~16mm in length including the terminals
A USB mains plug
A USB to 2.1mm jack cable
2x 15-25cm (6-10”) ~26 AWG wire - ideally in different colors (e.g. red and black).
For the 3D printed case, you will need the following bolts/screws:
2-4x M3x5mm - To mount the Arduino
4x M3x12mm - To join the front and rear of the case
2x M3x20mm - To mount the DHT22/DHT11 via the 14mm stand-offs
2x M3 nuts - For the DHT22/DHT11 stand-off bolts/screws
A note on accuracy
The DHT22 sensor is said to be accurate to within 0.5C and 5% humidity (the DHT11 is slightly less accurate). However, the electronic components used in this project generate heat, which can affect the sensor’s measurements.
In particular, the Arduino’s on-board voltage regulator generates a significant amount of heat, so we bypass the voltage regulator in this project by wiring a 5V power supply directly to the 5V pin and we mount the DHT22/DHT11 to the exterior of the case with an air-gap between the sensor and the case.
By doing this we’ve achieved temperature readings that are within 0.5-1.0C of independent thermometers.”