HardLabs

Freezer Monitor

k-meeks·Freezer_Monitor

This repository ships a schematic but no board layout.

About the Freezer Monitor PCB

Freezer Monitor is an open source Nordic nRF PCB design by k-meeks, published on GitHub. It is a board, with 10 components from 9 distinct parts.

Its main chip is the nice!nano nRF52840, from the Nordic nRF family. By type, the board carries 3 resistors, 2 connectors, 2 capacitors, 1 IC, 1 battery holder and 1 jumper.

It belongs with the iot & wireless, usb & debug tools and sensors designs in this gallery.

From the project

A battery-powered sensor that lives inside a chest freezer and reports temperature to Home Assistant via Bluetooth.

A battery-powered sensor that lives inside a chest freezer and reports temperature to Home Assistant via Bluetooth.

1. An nRF52840 wakes on a timer, reads a DS18B20 temperature sensor, measures battery voltage via an external resistor divider, and broadcasts both as a BTHome v2 Bluetooth Low Energy advertisement. 2. Home Assistant (with a Bluetooth adapter) picks up the advertisement directly via its built-in BTHome integration — no gateway required if HA has BT access near the freezer. 3. HA exposes temperature and battery as entities for dashboards, automations, and alerting.

Main components on the Freezer Monitor

nice!nano nRF52840

Freezer Monitor bill of materials (BOM)

10 components, 9 distinct parts.

QtyPartRefs
1
nice!nano nRF52840
U1
1
DS18B20
J1
1
SERIAL
J2
1
LS14250
BT1
1
BATT
JP1
1
100uF
C1
1
10nF
C2
2
1M
R1, R2
1
4.7k
R3

Freezer Monitor design files

The KiCad project lives in the k-meeks/Freezer_Monitor repository on GitHub; these links point at the commit this page was built from.

Freezer Monitor: common questions

What microcontroller does the Freezer Monitor use?

The Freezer Monitor is built around the nice!nano nRF52840, from the Nordic nRF family.

How many components are on the Freezer Monitor?

10 components, from 9 distinct parts. The full bill of materials is listed on this page.

Where can I download the Freezer Monitor design files?

From the k-meeks/Freezer_Monitor repository on GitHub, which has a netlist; the links under Design files point to each one.

Can I use the Freezer Monitor design in my own project?

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

Can I test firmware for the Freezer Monitor without the hardware?

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

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