FlyingRC RM3100 is an external compass module based on the three-axis PNI RM3100 magnetometer. The compass communicates via the SPI bus (MOSI, MISO), making it suitable for robotics and DIY projects. Before using it on RC airplane and drone models, make sure the flight controller has the SPI bus brought out. The module is not equipped with a connector or cable. Wires are soldered directly to the pads, or the module can be connected via a pin header.
The magnetometer senses the Earth's magnetic field, which is very weak and easily affected by surrounding electronics, especially battery power cables. The compass should therefore be placed as far away from the rest of the electronics as possible. A separate external module allows this, unlike a combined GPS with compass. The board is four-layer, 1.16 mm thick, with gold-plated pads. Its dimensions of 12.70 x 12.70 x 7.42 mm and weight of 0.53 g allow installation even on smaller builds.
The RM3100 module consists of two Sen-XY-f sensor coils for the X and Y axes, one Sen-Z-f coil for the Z axis, and a MagI2C controller. It works on a magneto-inductive principle, measuring the frequency of an oscillation circuit whose inductance changes with the surrounding magnetic field. Compared to common Hall sensors, the manufacturer states it offers roughly ten times higher resolution and more than twenty times lower noise, with no magnetic hysteresis and no need for temperature calibration.
Important notice: The compass communicates only via SPI. The Betaflight firmware does not support the RM3100 magnetometer. iNav supports it only on targets that have the SPI bus and the compass CS pin defined. ArduPilot and PX4 have a driver for the RM3100, but SPI wiring usually requires modifying hwdef and building a custom firmware version. Before purchasing, we recommend verifying that the flight controller really supports the RM3100 over SPI.
The module is powered exclusively by 3.3 V, operating range is 2.0-3.6 V. Supplying 5 V will destroy the module.
Key Features
- Input voltage: 3.3 V
- Magnetometer: PNI RM3100
- Communication interface: SPI
- Measurement range: ±400 µT
- Sensitivity: 13 nT
- Noise: 15 nT
- Linearity: 0.5 % (in the ±200 µT range)
- Repeatability: ≤8 nT (in the ±200 µT range)
- Magnetic hysteresis: ≤15 nT (in the ±200 µT range)
- Maximum sampling rate: 440 Hz (single axis)
- Connection: 8 solder pads (VCC, 2x GND, DRDY, CLK, MISO, MOSI, SSN)
- PCB: 4 layers, 1.16 mm thick, gold-plated pads
- Size: 12.70 x 12.70 x 7.42 mm
- Weight: 0.53 g
Package Includes
- 1x External compass
