Erriez Oregon THN128 433MHz temperature sensor library for Arduino Documentation

Oregon THN128 433MHz temperature transmit/receive library for Arduino

This is a 433MHz wireless 3-channel Oregon THN128 temperature transmit/receive Arduino library for ATMega328, ESP8266 and ESP32 using the (reverse-engineered) Oregon THN128 v1 protocol:

Transmit / receive hardware

This Arduino library can be used with low-power ATMega328 microcontroller (AVR architectures like Arduino UNO and Pro Mini 3.3V 8MHz boards).

Temperature transmitter on the left breadboard:

• Pro-Mini 3V3 8MHz.
• Genuine DS18B20 temperature sensor.
• STX802 low-power 433MHz transmitter.

Receiver on the right breadboard:

• SRX882 low-power 433MHz receiver.
• SSD1306 I2C 128x64 OLED display.
• Pro-Mini 3V3 8MHz.

Supported microcontrollers

• ATMega328 AVR designed for low-power
• ESP8266
• ESP32
• Other microcontrollers are not tested and may or may not work

Arduino Examples

• Oregon THN128 Receive
• Oregon THN128 Receive SSD1306 OLED
• Oregon THN128 Transmit random temperature
• Oregon THN128 Transmit DS1820 1-wire temperature sensor
• Oregon THN128 ESP32 MQTT Homeassistant

ESP32 with MQTT and Homeassistant

The Erriez_Oregon_THN128_ESP32_MQTT_Homeassistant.ino sketch can be used with Homeassistant integration.

Example screenshot Homeassistant dasboard:

Follow the steps below:

1. Configure Homeassistant MQTT in configuration.yaml:

mqtt:
  discovery_prefix: ha
  # Enable when using SSL:
  # certificate: /ssl/ca.crt
  # client_cert: /ssl/client.crt
  # client_key: /ssl/client.key

1. MQTT broker hostname, username and password should be configured in Homeassistant | Settings | Devices | MQTT.
2. Configure the listed macro's in the example, build and run from the Arduino IDE. The following Oregon THN128 entities are automatically registered after a succesful MQTT connection:

• sensor.oregon_thn128_ch1
• sensor.oregon_thn128_ch2
• sensor.oregon_thn128_ch3
• sensor.oregon_thn128_battery

1. Configure Homeassistant dashboard configuration file:

• Homeassistant Dashboard YAML

Hardware Design Notes

Supported hardware:

• AVR designed for low-power
• ESP8266
• ESP32
• For low-power transmitters, a Pro Mini 3V3 8MHz bare board with ATMega328 microcontroller is highly recommended. The board has no serial interface chip which reduces continuous power consumption. An external FTDI232 - USB serial interface should be connected for serial console / programming. (See red PCB on the picture) The SMD power LED should be desoldered from the Pro Mini to reduce continuous power consumption.
• A transmitter with (protected) 1500mA 18650 battery can operate for at least 6 months with LowPower.h functionality implemented. (By sending the temperature every 30 seconds)
• Changing the BOD (Brown Out Detection) fuse to 1.8V allows operation between 1.8 and 4.2V 18650 battery. (Explanation beyond the scope of this project)
• 1 to 3 temperature transmitters are supported, similar to the original Oregon THN128 temperature transmitters.
• Check list of counterfeit DS18B20 chips , because this makes a huge difference in accuracy and read errors at 3.3V. Many DS18B20 chips from Aliexpress are counterfeit and won't work
  reliable at voltages below 3.3V.
• NiceRF Wireless Technology Co., Ltd. sells high quality 433MHz transmit (STX802) and receiver modules (STX882) with a good range.
• A 18650 battery (with protection circuit) should be connected directly to the VCC pin (not VIN).
• The voltage regulator can be desoldered from the pro-micro board when not used for more power reduction.

Oregon Protocol

A packet is sent twice:

Data (see header file ErriezOregonTHN128Receive.h):

• Byte 0:
  • Bit 0..3: Rolling address (Random value after power cycle)
  • Bit 6..7: Channel: (0 = channel 1 .. 2 = channel 3)
• Byte 1:
  • Bit 0..3: TH3
  • Bit 4..7: TH2
• Byte 2:
  • Bit 0..3: TH1
  • Bit 5: Sign
  • Bit 7: Low battery
• Byte 3:
  • Bit 0..7: CRC

Library Changes

v1.1.0

The callback function void delay100ms() has been removed as this was not compatible with ESP32. The application should change the code to:

{c++}
   // Send temperature twice with 100ms delay between packets
   OregonTHN128_Transmit(&data);
   delay(100);
   OregonTHN128_Transmit(&data);

AVR targets can replace delay(100) with LowPower usage:

{c++}
   LowPower.powerDown(SLEEP_15MS, ADC_OFF, BOD_OFF);
   LowPower.powerDown(SLEEP_60MS, ADC_OFF, BOD_OFF);
   LowPower.powerDown(SLEEP_15MS, ADC_OFF, BOD_OFF);

Saleae Logic Analyzer

capture from the Oregon THN128 can be opened with https://www.saleae.com/downloads/.

Generated Arduino Library Doxygen Documentation

• Online Doxygen HTML
• Doxygen PDF

MIT License

This project is published under MIT license with an additional end user agreement (next section).

End User Agreement :ukraine:

End users shall accept the End User Agreement holding export restrictions to Russia to stop the WAR before using this project.