fancontrol

General

This program controls a fan to lower air humidity e.g. in basements. It uses two combined temperature and humidity sensors to calculate the approximate absolute humidity inside and outside. If the absolute humidity outside is lower than inside and the outside temperature is above the minimum temperature, the fan pin gets powered.

Features

configurable offset in humidity to operate
configurable minimum outside temperature to activate fan
many values can be shown on display
- absolute humidity (inside + outside)
- relative humidity (inside + outside)
- temperature (inside + outside)
- time that the fan was active (today + since last reset)
- runtime
logging via serial over USB
different DHT sensors may be used for in and outside (if they are compatible with the library)
flexible port configuration

Dependencies

DHT sensors: To read the sensors, Adafruits DHT sensor library is used and has to be downloaded seperately. https://github.com/adafruit/DHT-sensor-library
Display: The standard LiquidCrystal library is used to comminucate with the display

Hardware

To operate properly the following hardware are being used:

1x Arduino Uno
2x DHT22 temperature and humidity sensors
1x relay board to power up fan(s)
1x any 16x2 LCD display that is supported by the LiquidCrystal library (tested with JHD162a)
- peripherals (e.g. potentiometer for contrast current)

Connection

The listed hardware should be connected to the Arduino as follows (numbers are arduino ports):

2 => LCD DB7
3 => LCD DB6
4 => LCD DB5
5 => LCD DB4
6 => DHT data (inside)
7 => DHT data (outside)
8 => Relay
11 => LCD Enable
12 => LCD RS

(alternatively ports can be changed in software)

Additional connections to LCD ports (for JHD162a):

1 => GND
2 => VCC 5V
3 => Contrast Current
5 => GND
15 => VCC 4.2V (Backlight)
16 => GND (Backlight)

Configuration

You may decide what functionality exact you want by modifying config.h.