Northern Widget sensors
Apis
Measure range and orientation with a Garmin LiDAR Lite — power management, firmware watchdog, and MEMS accelerometer onboard. Hardware | Library | API reference
Skunkworks sensors
These sensors are in active development. They work, but documentation, packaging, and support are still catching up.
Walrus
Measure water levels (or atmospheric pressure) and temperature with this encapsulated sensor. Hardware | Library
Haar
Waterproof atmospheric temperature, pressure, and relative humidity sensor. Hardware | Library
Libelle
Spectrally resolved shortwave (solar) radiation sensor (pyranometer). Hardware | Library
Liasis
Longwave radiation sensor (pyrgeometer). Hardware | Library
Northern Widget prototypes
The following sensors are still in earlier stages of development.
Calypso
Dual-mode turbidity sensor: measures both transmission and scattering.
ThermalStake
Rugged subsurface temperature profiler: thermal conduction and fluid flow.
I2C address reference
When connecting multiple sensors to a shared I2C bus, each device must have a unique address. The table below lists the host-visible I2C address for every Northern Widget sensor. Last verified: 2026-05-14. Update this table whenever a sensor is added or a firmware default changes.
| Device | Default address | Configurable? | Notes |
|---|---|---|---|
| Apis | 0x50 |
Yes | Write new address to register 0x0C; firmware saves to EEPROM |
| Haar | 0x42 |
No | Hardcoded in ATtiny firmware |
| Libelle | 0x40 / 0x41 |
Hardware | 0x40 face up; 0x41 face down |
| Liasis | 0x4A |
No | Fixed by ADS1115 ADDR pin tied to GND |
| T9602 | 0x28 |
No | Fixed chip address |
| Tally | 0x33 |
Yes | Configurable via library |
| Walrus | 0x4D |
In development | EEPROM-based configuration being added to I2C firmware |
The Longbow RS-485-to-I2C bridge takes a user-assigned address and is not listed above.
Licenses
All designs and documentation are licensed under Creative Commons Attribution Share-Alike v4.0.
All code is licensed under the GNU GPL v3.0.
