Overview
Beitian M9 (M9140) GNSS CAN module series provides multi-constellation positioning data output for UAV and FPV drone flight control and other positioning projects. This series includes models BK-315, BK-318, BK-325, and BK-345, supporting GPS/GLONASS/BDS/GALILEO with SBAS/QZSS.
Beitian GNSS modules, antennas and receivers are widely used in UAV & FPV drones, flight control, aerial surveying and mapping, precision agriculture, geodetic survey, deformation monitoring, marine navigation, automotive positioning, industrial IoT, timing synchronization, robotics, Arduino DIY and other high-precision positioning fields.
Key Features
- Multi-mode positioning: GPS | GLONASS | BDS | GALILEO | SBAS | QZSS
- Built-in multiple interface outputs (series described as “GNSS CAN module”)
- NMEA-0183 message content listed: GGA, GLL, GSA, GSV, RMC, VTG
- Antenna network design: impedance matching (50Ω), antenna VSWR < 1.6
- Antenna detection and short-circuit protection function
- Support customization (debug/configuration per requirements)
Specifications
Common GNSS (BK-315 / BK-318 / BK-325 / BK-345)
| GNSS chip | M9140 |
| Receiver type | GPS, GLONASS, BDS, GALILEO |
| Auxiliary system | SBAS, QZSS |
| Channels | 92-channel |
| Cold start sensitivity | -148 dBm |
| Hot start sensitivity | -159 dBm |
| Horizontal position accuracy | 1.5 m CEP |
| Velocity accuracy (parameter table) | 0.05 m/s |
| Time pulse accuracy | RMS 30 ns; 99% 60 ns |
| Cold start time | 24 s |
| Hot start time | 2 s |
| Aided start | 2 s |
| Baud rate | 4800–921600 bps (BK-315 default 9600; BK-318/BK-325/BK-345 default 38400) |
| Output level | TTL level |
| Output protocol | NMEA, UBX |
| Update rate | 0.25–25 Hz (default 1 Hz) |
| Operating temperature | -40°C to +85°C |
| Storage temperature | -40°C to +105°C |
Frequencies / Satellite Systems (listed)
| Working mode | GPS, GLONASS, BDS, GALILEO |
| Frequency | GPS L1 C/A; QZSS L1 C/A/S; GLONASS L10F; BDS B1I; Galileo E1B/C; SBAS L1 C/A (WAAS, EGNOS, MSAS, GAGAN) |
| Antenna marking (shown) | BDS L1 - GLS G1: 1561 MHz - 1602 MHz |
BK-315
| Dimensions | φ55.8 × 9.8 mm |
| Weight | 32 g |
| Current | 120 mA |
| VCC | DC: 5.0 V |
| Connector | 1.25 mm 6PIN × 2 |
| Peripherals / Compass | QMC5883 |
| MCU | Arm Cortex-M3 MCU, 72 MHz, 128 Kbytes Flash, 20 Kbytes SRAM |
| Peripherals | CAN2.0 A/B |
| Interface | N/A |
| CAN LED | Green light, slow blinking after successful CAN communication |
| PPS LED | Red light is steady on after powering on, and flashes after positioning |
| TX LED | Blue light flashes when there is an output |
BK-318
| Dimensions | φ55.8 × 9.8 mm |
| Weight | 32 g |
| Current | 120 mA |
| VCC | DC: 5.0 V |
| Connector | 1.25 mm 6PIN × 2 |
| Peripherals / Compass | QMC5883 |
| MCU | Arm Cortex-M3 MCU, 72 MHz, 128 Kbytes Flash, 20 Kbytes SRAM |
| Peripherals | CAN2.0 A/B |
| Interface | N/A |
| CAN LED | Green light, slow blinking after successful CAN communication |
| PPS LED | Red light is steady on after powering on, and flashes after positioning |
| TX LED | Blue light flashes when there is an output |
BK-325 (detailed parameters shown)
| Chip | M9140-KB |
| Sensitivity (Trace) | -167 dBm |
| Sensitivity (Recapture) | -160 dBm |
| Dynamic heading angle accuracy | 0.3 deg |
| NMEA statements (listed) | RMC, VTG, GGA, GSA, GSV, GLL |
| Update frequency | 0.25–25 Hz (default 1 Hz) |
| FLASH | With FLASH, the configuration can be changed, and the power will not be lost |
| Second pulse | Configurable from 0.25 Hz to 10 MHz; default period 1 s; high level lasts for 100 ms |
| Work restrictions (Altitude) | 80,000 m |
| Work restrictions (Speed) | 500 m/s |
| Work restrictions (Acceleration) | <= 4 g |
| MCU | STMicroelectronics Cortex-M4 (STM32F412RET6), FLASH 512 KB, SRAM 256 KB, 100 MHz, LQFP-64 (10x10) |
| Peripherals | Geomagnetic sensor RM3100; Barometric pressure sensor MS5611 |
| CAN interface | CAN2.0 A/B, Max 1 Mbit/s; CUAVCAN |
| Power | DC: 5.0 V; 120 mA |
| Size | φ55.8 × 11.8 mm |
| Weight | 33 g |
| Connectors | 1.25 mm 4 pin; 1.25 mm 5 pin; 1.25 mm 6 pin |
| LED (FIX) | Red light stays on when power is on |
| LED (CAN) | Green light flashes during CAN communication |
| LED (SAFETY) | Purple light safety switch light |
| LED (RGB) | 8 colored lights (valid when there is MCU) |
BK-345
| Dimensions | φ55.8 × 11.8 mm |
| Weight | 33 g |
| Current | 120 mA |
| VCC | DC: 5.0 V |
| Connector | 1.25 mm 4PIN × 3 |
| MCU | ARM Cortex-M4 32-bit, STM32F405RGT6, 168 MHz frequency, 192+4 KB SRAM, 1 MB Flash |
| Peripherals | Geomagnetic sensor RM3100; Barometric pressure sensor MS5611; SD NAND Flash, 4 GB |
| Interface | CAN2.0 A/B, Max 1 Mbit/s; USB2.0, full-speed |
| PPS LED | If not positioned, the light will not be on; after 3D positioning, the green light will flash |
| Red/Yellow LED | MCU software decides |
Published test values (also shown)
| Capture sensitivity test | Trace -167 dBm; Recapture -160 dBm; Cold boot -148 dBm; Warm boot -159 dBm |
| Positioning accuracy test | Horizontal accuracy 1.5 rice CEP; Speed accuracy 0.5 m/s; Dynamic heading accuracy 0.3 deg; Temporal precision RMS 30 ns / 99% 60 ns |
| Start time test | Cold boot 24 s; Assisted start-up 2 s; Warm boot 2 s |
| Power consumption test | Voltage: 3.6 V–5.5 V (Typical: 5.0 V); Current: 25 mA / 5.0 V |
Pinout / Wiring (listed for BK-325)
MCU (UART, TTL level)
| PIN 1 | 5V | I | Default 5.0 V |
| PIN 2 | TX | O | UART communication interface, TTL level |
| PIN 3 | RX | I | UART communication interface, TTL level |
| PIN 4 | DIO | I | MCU programming interface |
| PIN 5 | CLK | I | MCU programming interface |
| PIN 6 | GND | G | Ground |
MCU CAN
| PIN 1 | 5V | I | Default 5.0 V |
| PIN 2 | CANH | I | CANH communication interface |
| PIN 3 | CANL | I | CANL communication interface |
| PIN 4 | GND | G | Ground |
Applications
- UAV and FPV drones, flight control
- Aerial surveying and mapping
- Precision agriculture
- Geodetic survey, deformation monitoring
- Marine navigation, automotive positioning
- Industrial IoT, timing synchronization
- Robotics and Arduino DIY positioning projects
For model selection (BK-315/BK-318/BK-325/BK-345) and integration support, contact support@rcdrone.top or visit https://rcdrone.top/.
Details

Debug and configuration support is available, with development files provided to speed up integration.

Choose the right module variant by comparing key parameters across BK-315, BK-318, BK-325, and BK-345.

Multi-constellation GNSS support helps deliver stable positioning data for UAV and FPV flight controllers.

Standard NMEA outputs (GGA/GLL/GSA/GSV/RMC/VTG) make it easy to parse location, speed, and status data.

Onboard processing and sensor expansion support reliable navigation builds with compact, low-power hardware.

Performance test results summarize sensitivity, accuracy, start times, and power draw for quick evaluation.

BK-325 pin labeling and core specs are provided for straightforward wiring to flight control systems.

Pin definitions and wiring guidance cover CAN and UART connections for controller integration.

Clear IO mapping supports quick bench setup, along with module photos for BK-315 and BK-318 identification.

Module close-ups highlight the board layout and antenna marking details for BK-325 and BK-345.

Beyond drones, the module suits robotics, industrial computers, and automation projects needing GNSS positioning.
