SparkFun
SparkFun GPS-RTK Dead Reckoning pHAT for Raspberry Pi
· MPN: GPS-21305
The SparkFun GPS-RTK Dead Reckoning pHAT brings high-precision GNSS positioning with automotive dead reckoning to the Raspberry Pi. Built around the u-blox Z...
The SparkFun GPS-RTK Dead Reckoning pHAT brings high-precision GNSS positioning with automotive dead reckoning to the Raspberry Pi. Built around the u-blox ZED-F9R module, it fuses GNSS measurements with an integrated 3D IMU (accelerometer and gyroscope), wheel ticks, and a vehicle dynamics model to maintain accurate positioning even under poor signal conditions.
The 184-channel ZED-F9R receives GPS, GLONASS, Galileo, and BeiDou signals on L1 and L2 bands, achieving 10 mm horizontal accuracy with RTK corrections. Position updates run at up to 30 Hz, and dead reckoning maintains continuous positioning through tunnels, parking garages, and urban canyons where satellite signals are blocked or degraded.
Pre-soldered headers allow the pHAT to stack directly onto a Raspberry Pi or any single-board computer with a 2×20 GPIO header (including NVIDIA Jetson Nano and Google Coral). Communication uses the Pi's serial UART by default. A Qwiic (I²C) connector and additional 2.54 mm breakout pins are also available.
Key Features
- u-blox ZED-F9R Module – 184-channel multi-constellation GNSS receiver with integrated 3D IMU for dead reckoning
- 10 mm RTK Accuracy – Centimetre-level horizontal positioning with correction data (rover only; requires base station)
- Dead Reckoning – Continuous positioning through signal loss using sensor fusion
- 30 Hz Navigation Rate – High-rate position updates for real-time applications
- Dual-Band Reception – L1C/A and L2C for improved accuracy and faster convergence
- Pre-Soldered Headers – No soldering required; stacks directly onto the Pi GPIO header
- Onboard RTC Battery – Reduces time-to-first-fix from ~24 s (cold) to ~2 s (hot start)
- U.FL Antenna Connector – Use with an external active GNSS antenna
- Qwiic Connector – I²C interface for additional peripherals
Specifications
- Constellations – GPS, GLONASS, Galileo, BeiDou (concurrent)
- Horizontal Accuracy – 10 mm with RTK
- Velocity Accuracy – 0.5 m/s
- Heading Accuracy – 0.2°
- Time Pulse Accuracy – 30 ns
- Max Navigation Rate – 30 Hz
- Operational Limits – ≤ 4 G, 80 km altitude, 500 m/s velocity
- Protocols – NMEA, UBX, and RTCM over UART
- Voltage – 5 V or 3.3 V (all logic is 3.3 V)
- Current Draw – ~85–130 mA (varies with constellation tracking)
- Board Dimensions – 65.0 × 56.5 mm
- Weight – 20.7 g
Software Features
- Configurable via u-blox u-center (Windows)
- Geofencing, odometer, and spoofing detection
- External interrupt and pin control
- Low power mode
Ideal For
- Autonomous robotics and vehicle navigation
- Precision positioning in urban environments
- Fleet tracking with dead reckoning through tunnels and covered areas
- Raspberry Pi-based GNSS data logging
Package Contents
- 1× SparkFun GPS-RTK Dead Reckoning pHAT (v1.1)
Resources
Jargon buster
Plain-language definitions for the technical terms used above.
- Active GNSS antenna
- An active GNSS antenna has a built-in amplifier that needs power from the board. It can improve satellite signal reception, but you need to use an antenna that matches the board’s powered antenna connection.
- breakout
- A breakout is a small circuit board that makes a tiny or hard-to-solder component easier to connect to with standard pins. It matters because this OLED module can be wired into a microcontroller project without needing to solder directly to the display’s fine contacts.
- Galileo
- Europe’s satellite navigation system. Galileo support can improve satellite availability and accuracy, especially when combined with GPS and other constellations.
- GLONASS
- Russia’s satellite navigation system. A receiver that can also use GLONASS has more satellites to choose from, which can improve positioning reliability when the sky view is partly blocked.
- GNSS
- GNSS stands for Global Navigation Satellite System, covering positioning systems such as GPS and similar satellite networks. It matters here because high-precision GNSS modules can output lots of serial position data that this product can send wirelessly to a computer or phone.
- GPIO
- General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
- GPS
- The US satellite navigation system used by GNSS receivers to calculate position and time. Support for GPS is important because it is widely available and often used together with other constellations for more reliable positioning.
- Gyroscope
- A gyroscope measures rotation, such as how fast a board is turning around its X, Y, and Z axes. This matters for projects like gesture controls, balancing robots, and motion tracking where tilt or rotation changes need to be detected.
- Headers
- Rows of metal pins used to plug a module into a breadboard or connect it with jumper wires. Pre-soldered headers make the module easier to use straight away without needing to solder the pins yourself.
- IMU
- An Inertial Measurement Unit combines motion sensors to measure movement and orientation. It matters for asset tracking because it can detect movement, tilt, vibration, or changes in direction.
- L1C/A
- A GPS signal band used by many GNSS receivers for standard positioning. Support for this band helps determine which satellite signals the receiver can use and how well it can maintain a location fix.
- L2C
- A second GPS signal band used by dual-band GNSS receivers to improve precision and reduce errors caused by the atmosphere. It matters for RTK and high-accuracy applications because using two bands can produce faster and more reliable centimetre-level fixes.
- NVIDIA Jetson Nano
- A compact NVIDIA computing module used for camera, robotics and machine-learning projects at the edge. Compatibility with Jetson Nano tells you this carrier board can host that module, but the module itself is not included.
- pHAT
- A smaller add-on board format for Raspberry Pi, similar in idea to a HAT but usually not full-sized. It matters because pHAT compatibility can affect how neatly a board stacks or fits into a Raspberry Pi project.
- Qwiic
- Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
- RTC
- A Real-Time Clock keeps track of time even when the main processor is asleep or powered down, usually with a small backup battery. It matters for data logging and tracking projects that need accurate timestamps.
- RTK
- Real-Time Kinematic positioning is a GNSS technique that uses correction data from a base station to greatly improve location accuracy. It matters if you need centimetre-level positioning for robotics, mapping, surveying, or tracking rather than ordinary metre-level GPS accuracy.
- single-board computer
- A complete computer built onto one circuit board, usually including the processor, memory, ports, and connectors. This matters because accessories like heatsinks must match the board’s layout and mounting holes to fit properly.
- u.FL
- u.FL is a tiny snap-on antenna connector often used on compact wireless boards. A board with u.FL usually needs an external antenna, which matters if the product will be inside an enclosure or needs better antenna placement.
- UART
- UART is a simple serial connection that sends data over separate transmit and receive wires, often labelled TX and RX. It matters because this module is designed to replace a wired UART cable with a wireless link while keeping the same serial data format.
Find this product in
Brands
Sensors & Input
GPS-RTK Dead Reckoning pHAT Schematic
Schematic · 443.1 KB · Click any page to view full size
u-blox ZED-F9R Datasheet
Datasheet · 2.6 MB · Click any page to view full size
u-blox ZED-F9R Product Summary
Product Brief · 115.7 KB · Click any page to view full size
u-blox ZED-F9R Integration Manual
User Guide · 11.6 MB · Click any page to view full size
u-blox F9 Interface Description
User Guide · 3.3 MB · Click any page to view full size
u-blox ECCN Document
Compliance · 27.8 KB · Click any page to view full size
Supplier page — sparkfun.com
Supplier Description · 811.8 KB · Click any page to view full size
Resources & Downloads
Guides, code examples, and more