https://github.com/crycode-de/attiny85-radiohead-dht22-weather-sensor

Arduino sketch for using an ATtiny85 microprocessor and a DHT22 humidity/temperature sensor as a battery powered weather station.
https://github.com/crycode-de/attiny85-radiohead-dht22-weather-sensor

arduino-ide attiny85

Last synced: about 2 months ago
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Arduino sketch for using an ATtiny85 microprocessor and a DHT22 humidity/temperature sensor as a battery powered weather station.

• Host: GitHub
• URL: https://github.com/crycode-de/attiny85-radiohead-dht22-weather-sensor
• Owner: crycode-de
• Created: 2023-02-01T12:03:22.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2023-02-01T12:03:49.000Z (over 3 years ago)
• Last Synced: 2026-01-01T10:22:50.608Z (6 months ago)
• Topics: arduino-ide, attiny85
• Language: C++
• Homepage:
• Size: 1.04 MB
• Stars: 1
• Watchers: 1
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# ATtiny85 RadioHead DHT22 Weather Station

Arduino sketch for using an ATtiny85 microprocessor and a DHT22 humidity/temperature sensor as a battery powered weather station.

The measured values are transmitted using [RadioHead](http://www.airspayce.com/mikem/arduino/RadioHead/) and a 433MHz radio module.

[![breadboard](https://cdn.cryhost.de/arduino/attiny85-radiohead-dht22-weather-sensor-breadboard.png)](https://cdn.cryhost.de/arduino/attiny85-radiohead-dht22-weather-sensor-breadboard.png)

## Power supply

The power supply consists of 3 AA batteries and on DC boost converter.

The boost converter takes 0.6V to nearly 5V and gives a stable output of 5V.

## Power saving

The ATtiny85 is sleeping most of the time in power down mode.

The watchdog wakes the controller up every 8 seconds.

After 7 wake ups the temperature and humidity are measured and transmitted.

Additionally every 30 measurements the battery status is read using the ADC.

## Transmitted RadioHead messages

There are four different types of transmitted messages.

### Start message

This message is transmitted once if the controller starts.

It's one byte containing `0x00`.

### Temperature and humidity

This is a 9 byte message starting with the code `0x01`, followed by 4 byte temperature and 4 byte humidity as float using the little-endian format.

`0x01 t t t t h h h h`, e.g. `0x01 0xcd 0xcc 0xd0 0x41 0xcd 0xcc 0x4e 0x42`

### Battery status

This is a 3 byte message starting with the code `0x02`, followed by one byte with the battery percentage (0 to 100) and one byte with the raw ADC value (0 to 255).

e.g. `0x02 0x64 0xe7`

### Error message

If an error occurred during temperature/humidity measuring this one byte error message containing `0xee` is sent.

## ATtiny85 in ArduinoIDE

To be able to program an ATtiny microprocessor you need to add the following boards-manager URL and install the `attiny` package.

`https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json`

## License

Licensed under GPL Version 2

Copyright (c) 2017 Peter Müller  (https://crycode.de/)