This product has been replaced with a fancy red version. Everything is the same except the red version has better TX/MISO and RX/MOSI pin labels, and better hookup guide documentation.

Thanks to GPS you can quickly know where you are anywhere on the globe within 30 seconds. Pretty impressive! But what if you need better accuracy than the 2.5 meters accuracy that GPS provides? GPS Real Time Kinematics (RTK) has 25mm accuracy. You can now know where you are (or any object) within one inch.

The SparkFun GPS-RTK board is a powerful breakout board for the the NEO-M8P-2 module from Ublox. The NEO-M8P-2 module is the top-of-the-line module for high accuracy GNSS and GPS location solutions including RTK. The NEO-M8P-2 is unique in that it is capable of both rover and base station operations. The ‘-2’ designation means this module has survey-in mode allowing the module to become a base station and produce RTCM 3.x correction data.

The GPS-RTK has four communications ports:

• USB (enumerates as a COM port)
• UART (3.3V TTL)
• I²C
• SPI

The USB and UART ports are common and well documented. We've also written an Arduino library for Ublox modules to make reading and controlling the GPS-RTK over Qwiic a breeze.

We've even included a rechargable backup battery to keep the latest module configuration and satellite data available for up to two weeks. This battery helps 'warm-start' the module decreasing the time-to-first-fix dramatically.

We've written multiple tutorials to get you started:

• What is GPS RTK?
• Hookup guide for the GPS-RTK
• How to use U-Center

The number of configuration options of the NEO-M8P-2 is incredible! Geofencing, variable I2C address, variable update rates, even the high precision RTK solution can be increased to 4Hz. This is a powerful module.

What can we do on the next rev of this product to make it better? (a one question google form)

• Weight: 6.3g
• Dimensions: 1.6x1.3"
• Voltage: 5V or 3.3V but all logic is 3.3V
• Current: approximately 35mA (varies with constellations and tracking state)
• Time to first fix: 29s (cold), 1s (hot)
• Max Navigation Rate:
  • PVT (basic location over UBX binary protocol) - 10Hz
  • RTK - 5Hz
  • Moving Baseline RTK - 4Hz
  • Raw - 10Hz
• Horizontal Position Accuracy:
  • 2.5m without RTK
  • 0.025m with RTK

• What is GPS RTK?
• GPS-RTK Hookup Guide
• Using U-Center to configure the NEO-M8P for base station RTCM output
• SparkFun GPS-RTK Schematic
• NEO-M8P-2 Datasheet
• NEO-M8P Hardware Integration Manual
• NEO-M8P Product Summary
• Ublox M8 series protocol
• Ublox white paper on using low cost antennas for RTK
• Example RTCM output from the NEO-M8P-2
• SparkFun Ublox Arduino Library for reading NMEA and sending UBX commands over I2C. Can also be installed using the Arduino library manager by searching 'SparkFun Ublox'
• Check the hardware repo for the latest Eagle files
• Ublox ECCN notice