AVRThermostat

AVRThermostat is, as the name implies, a programmable thermostat, which is built on

• Atmel AVR ATmega8A microcontroller,

• digital thermometer DS18B20 by Maxim Integrated,

• four-digit seven-segment led display with common cathode (like CC56-12 or FYQ-5641A),

and uses a relay to control a heater or fan. The device can be used as a simple thermometer as well. The sensor measures temperatures from -55°C to +125°C with ±0.5°C accuracy from -10°C to +85°C.

The thermostat has 4 buttons (Plus, Minus, Set, Reset) that are used to set up parameters--the setpoint and the zone (delta). The longer you hold the Plus/Minus button, the faster a parameter increases/decreases. The Reset button is used to set the standard value to a parameter, also to switch off the thermostat mode. Parameters are saved in EEPROM after editing.

The Plus/Minus buttons also are used to adjust the display brightness when the device is not in the mode of editing of a parameter.

Two leds indicate the state of the relay. If the device is not in the thermostat mode, then both leds do not light.

If the device cannot establish connection with the sensor, the display shows an error.

Schematics and PCB Layout r3.x

A KiCad project, which includes a schematics and PCB layout, is located in the Design directory. Please be aware that the project is made from scratch and I have not yet used the new PCB layout myself, therefore it may have errors.

Schematics

PCB 3D Model

Versioning

For transparency and insight into our release cycle, and for striving to maintain backwards compatibility, AVRThermostat will be maintained under the Semantic Versioning guidelines as much as possible.

For more information on SemVer, please visit http://semver.org/

License

Copyright 2014-2017 Artyom Protaskin

Licensed under the MIT License:

http://opensource.org/licenses/MIT