HardLabs

Thermostat

jamesrwaugh·thermostat·hardware/Thermostat/Thermostat.kicad_pcb

Thermostat PCB layout, top view — open source AVR/Arduino board by jamesrwaugh

About the Thermostat PCB

Thermostat is an open source AVR/Arduino PCB design by jamesrwaugh, published on GitHub. It is a 2-layer board measuring 111.2 × 76.5 mm, with 39 components from 25 distinct parts.

Its main chip is the ATmega168P-20A, from the AVR/Arduino family. Other key parts include the GU112X16G-7003BL, 47L04, UA78M05QDCYRQ1, DS1307Z+ and SHT4x. By type, the board carries 10 capacitors, 7 ICs, 6 switches, 4 connectors, 4 relays and 4 resistors.

From the project

AVR-based Residential Thermostat Hardware / Firmware

- [End Goal] Home Assisstant integration compatible - Plugs into residential connections offering 24VAC power - Programmable time/day-based temperature settings - Heating, cooling, and off modes - Battery-backed storage for settings and time - Support on-cool and on-heat reverse valve types - Auto or always-on fan setting - Display in Fahrenheit or Celsius - ISP header for firmware flashing and updates - Objectively gorgeous vacuum-florescent display - Runs on a familiar, lovable AVR - All this and more, in a small & tiny 16Kb firmware binary

Main components on the Thermostat

GU112X16G-7003BL47L04UA78M05QDCYRQ1ATmega168P-20ADS1307Z+SHT4x

Thermostat bill of materials (BOM)

39 components, 25 distinct parts.

QtyPartRefs
1
GU112X16G-7003BL
U1
1
47L04
U2
1
~
U3
1
UA78M05QDCYRQ1
U4
1
ATmega168P-20A
U5
1
DS1307Z+
U8
1
SHT4x
U9
1
Crystal
Y1
1
Crystal
Y3
1
Conn_01x02_Pin
J2
1
AVR-ISP-6
J3
1
MainConnectorr
J4
1
Screw_Terminal_01x02
J5
1
Battery_Cell
BT1
4
G6E
K1, K2, K3, K4
5
12MM
SW1, SW2, SW3, SW7, SW9
1
SW_Push
SW5
1
SS33
D1
1
10uF
C1
2
1uF
C2, C3
Show 5 more
QtyPartRefs
2
22pF
C4, C5
4
0.1uF
C6, C8, C9, C10
1
6.8uF
C7
1
10k
R1
3
4.7k
R2, R6, R7

Thermostat design files

The KiCad project lives in the jamesrwaugh/thermostat repository on GitHub; these links point at the commit this page was built from.

Thermostat: common questions

What microcontroller does the Thermostat use?

The Thermostat is built around the ATmega168P-20A, from the AVR/Arduino family.

How big is the Thermostat PCB?

The Thermostat measures 111.2 × 76.5 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Thermostat?

39 components, from 25 distinct parts. The full bill of materials is listed on this page.

Where can I download the Thermostat design files?

From the jamesrwaugh/thermostat repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Thermostat design in my own project?

The repository has no license, so all rights stay with jamesrwaugh. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the Thermostat without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug AVR/Arduino firmware against it before you order a PCB.

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