HOLYBRO PMW3901 Optical Flow Sensor

HOLYBRO PMW3901 Optical Flow Sensor – Compact UART Sensor for PX4 and ArduPilot

The HOLYBRO PMW3901 Optical Flow Sensor is an extremely compact and lightweight optical flow sensor for detecting horizontal movement of UAVs and other unmanned systems. The module is based on the proven PMW3901 optical flow sensor and communicates directly with the flight controller via a UART interface.

An integrated BEC allows operation within a voltage range of 3.3 to 5.2 V. The sensor is supplied with a pre-installed 6-pin JST-GH cable, allowing it to be connected directly to a compatible TELEM port on many flight controllers.

The PMW3901 is compatible with PX4 and ArduPilot and is particularly suitable as an additional motion source for multicopters and other autonomous platforms. Optical flow can support position control, for example in environments where GNSS signals are unavailable or limited.

Optical Motion Detection

The PMW3901 detects relative movement over a visible surface. Motion data for the X and Y axes are generated from the displacement of the detected surface structure and transmitted to the flight controller via UART.

In combination with additional sensor information, the flight controller can use these data for motion and position estimation. This makes optical flow particularly useful for indoor applications and other environments with limited GNSS availability.

UART Interface

Communication is provided via a UART interface with a baud rate of 19,200 baud. Thanks to the pre-installed JST-GH connection, the module can be easily connected to a compatible serial port on the flight controller.

• Interface: UART
• Baud Rate: 19,200 baud
• Connector: 6-pin JST-GH
• Cable Length: 170 mm

Compatible with PX4 and ArduPilot

The HOLYBRO PMW3901 Optical Flow Sensor supports the widely used PX4 and ArduPilot autopilot platforms. The data format corresponds to that of the earlier CX-OF optical flow sensor and can therefore be integrated into compatible ArduPilot systems accordingly.

95 Hz Update Rate

The sensor operates at an update rate of 95 Hz. This allows motion information to be continuously captured and transmitted to the flight controller via the UART connection.

Integrated BEC

The module features an integrated BEC and supports a supply voltage of 3.3 to 5.2 V. Typical current consumption is only 10 mA, resulting in minimal additional load on the system power supply.

• Supply Voltage: 3.3–5.2 V
• Current Consumption: 10 mA
• Integrated BEC

Compact and Lightweight Design

With dimensions of only 14 × 11 × 5 mm and a weight of just 0.6 g, the PMW3901 can be integrated even into compact UAV platforms. The extremely low weight is particularly beneficial for small multicopters and weight-optimized systems.

Features

• Compact PMW3901 optical flow sensor
• Optical detection of horizontal movement
• UART communication
• 19,200 baud transmission rate
• 95 Hz update rate
• Integrated BEC
• Supply voltage from 3.3 to 5.2 V
• Only 10 mA current consumption
• Pre-installed 6-pin JST-GH connection
• Direct connection to compatible TELEM ports
• Compatible with PX4
• Compatible with ArduPilot
• Extremely compact dimensions
• Only 0.6 g weight
• TPU protective housing included

Technical Specifications

• Product Type: Optical Flow Sensor
• Sensor: PMW3901
• Interface: UART
• Baud Rate: 19,200 baud
• Update Rate: 95 Hz
• Supply Voltage: 3.3–5.2 V
• Current Consumption: 10 mA
• Dimensions: 14 × 11 × 5 mm
• Weight: 0.6 g
• Connector: 6-pin JST-GH
• Cable Length: 170 mm
• Firmware Compatibility: PX4 and ArduPilot

Data Format

The motion information detected by the sensor is transmitted to the flight controller via UART in a defined data packet. In addition to X- and Y-axis motion values, the packet includes a checksum and a value representing the detected surface quality.

• Byte 0: Header (0xFE)
• Byte 1: Number of Data Bytes (0x04)
• Byte 2: X-Motion High Byte
• Byte 3: X-Motion Low Byte
• Byte 4: Y-Motion High Byte
• Byte 5: Y-Motion Low Byte
• Byte 6: Checksum
• Byte 7: Surface Quality
• Byte 8: Footer (0xAA)

Operation in GNSS-Limited Environments

Optical flow sensors can be an important addition for UAVs operating indoors or in other environments with limited GNSS reception. The sensor provides the flight controller with information about relative horizontal movement over a surface.

For complete position estimation, optical flow is commonly combined with additional sensors. In particular, an additional distance measurement may be required so that the flight controller can correctly interpret the optically measured movement in relation to the flight altitude.

Package Contents

• 1 × HOLYBRO PMW3901 Optical Flow Sensor
• 1 × GH6P Cable, 170 mm, pre-installed
• 1 × TPU Protective Housing

Ultra-Lightweight Optical Flow Sensor for Unmanned Systems

The HOLYBRO PMW3901 Optical Flow Sensor provides a compact solution for integrating additional motion information into a UAV or autonomous platform. Thanks to the UART interface, integrated BEC, and pre-installed JST-GH cable, the module can be integrated into compatible flight controller systems with minimal effort.

With a weight of only 0.6 g, the sensor is particularly suitable for compact multicopters, development platforms, and custom unmanned systems based on PX4 or ArduPilot.