This Arduino project checks the temperature and turns on an outlet using a relay when the temperature has exceeded the upper limit of a defined range, then turns it off again when the sensor has reached the bottom temperature of the defined range.
It uses an Arduino Uno, an LCD module for display, a temperature/humidity sensor, and a relay.
This was designed for a beer fermenter refrigerator, so that we can simply power on/off the appliance according to the inside temperature without altering any of the electronics on the fridge.
Arduino LCD RioRand® LCD Module for Arduino 20 x 4, White on Blue http://www.riorand.com/electronics/riorandtm-lcd-module-for-arduino-20-x-4-white-on-blue.html Datasheet: https://cdn-shop.adafruit.com/datasheets/TC2004A-01.pdf
Pin # Function 1 VSS (Gnd) 2 VDD (+5V) 3 Contrast Adjustment - Connect the center tap of a 10k pot connected between Gnd and 5V 4 RS Register Select Input 5 R/W Read/Write Signal, normally at Gnd 6 E Enable 7 DB0 8 DB1 9 DB2 10 DB3 11 DB4 12 DB5 13 DB6 14 DB7 15 LED (+) (+5V through a current limiting resistor - I used 220ohm) 16 LED (-) Gnd
The Arduino connections are as follows: LCD Pin: Arduino Pin: RS D12 E D11 DB4 D5 DB5 D4 DB6 D3 DB7 D2
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Project Breadboard. All Arduino pins are Digital.
LCD screen pin outs
- black wire to breadboard: Left Side of 10K pot. also jumped to - rail
- orange wire to breadboard: right side of 10K pot. also jumped to + rail
- yellow/black wire to breadboard: center of 10K pot
- yellow wire to arduino pin 12
- orange wire to arduino GND
- brown wire to arduino pin 11
- not used
- not used
- not used
- not used
- white wire to arduino pin 5
- green wire to arduino pin 4
- purple wire to arduino pin 3
- blue wire to arduino pin 2
- red wire to breadboard: resistor (200K??) to + rail
- brown wire to breadboard: - rail
Temp/Humidity Sensor pin outs DAT pin to arduino pin 8 VCC pin to + rail GND pin to - rail
Relay https://www.amazon.com/RobotDyn-Thyristor-channel-Switch-Solid/dp/B072WQTBPQ/ref=sr_1_16
VCC connected to relay pin 13 GND connected to - rail