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Hardware Overview

The RTK Facet mosaic is a fully enclosed and pre-programmed device. There are very few things to worry about or configure, but we will cover the basics here.

Design Files

The design of the SparkPNT RTK Facet mosaic L-Band is similar to previous generations in our line Facet line of products. However, we have made some modifications to the design to enhance the durability of this product. The PCB design features three separate board components:

  • A central board that hosts primary components of the RTK Facet mosaic, such as the ESP32-WROVER-E, mosaic-X5, etc.
  • A peripheral board that provides connections to the RTK Facet mosaic
  • A display board that is the primary interface for the RTK Facet mosaic

Replacement Parts

Kit Parts
Internal Components
  • M2.2-0.98 x 10mm Thread Forming Screws - Phillips Head
  • M3-1.34 x 10mm Thread Forming Screws - Phillips Head

Power/Setup Button

RTK Facet mosaic Front Face

The POWER/SETUP button on the front of the RTK Facet mosaic.

The RTK Facet mosaic has a POWER/SETUP button to turn the device on/off or for in-field configuration changes.

  • Press and hold the button down, to power the RTK Facet mosaic ON or OFF.
  • Short presses of the button will cause the RTK Facet mosaic to change modes. This device can be used in five modes:
    • Rover
      • GNSS Positioning (~30cm accuracy) - also known as Rover
      • GNSS Positioning with RTK (1.4cm accuracy) - also known as Rover with RTK Fix
      • GNSS Positioning with RTK L-Band (1.4 to 6cm accuracy) - also known as Rover with L-Band RTK Fix
    • Base
      • GNSS Base Station
      • GNSS Base Station as NTRIP Server

Power Switch

RTK Facet mosaic startup display with firmware version number

The splash screen of RTK Facet mosaic display showing the firmware version number and the device powering off.

The Power button turns the unit on or off:

  • Press and hold the power button until the display illuminates.
  • Press and hold the power button at any time to turn the unit off.

Battery Power

RTK Facet mosaic showing the battery level

RTK Facet mosaic display, showing the battery level.

The RTK Facet mosaic has a large, built-in 6000mAh lithium polymer battery that will enable over 25 hours of field use between charging. If more time is needed a common USB power bank can be attached boosting the field time to any amount needed.

Info

For more information, please refer to the Internal Batter section

Charge LED

RTK Facet mosaic Charge LED

Charge LED indicator on the RTK Facet mosaic.

The Charge LED is located on the front face. It will illuminate any time there is an external power source and will turn off when the internal battery is charged. With the unit fully powered down, charging takes approximately 6 hours from a 1A wall supply or 12 hours from a standard USB port. The RTK Facet mosaic can run while being charged but it increases the charge time. Using an external USB battery bank to run the device for extended periods or running the device on a permanent wall power source is supported.

Operation Modes

At Power On the device will enter Rover or Base mode; whichever state the device was in at the last power down. When the POWER/SETUP button is pressed momentarily, a menu is presented to change the RTK Facet mosaic from Rover to Base mode or vice-versa. The display will indicate the change with a small car (Rover) or flag (Base) icon.

Rover Mode

In Rover mode the RTK Facet mosaic will receive L1, L2, and L5 GNSS signals from the four constellations (GPS, GLONASS, Galileo, and BeiDou) and calculate the position based on these signals. Similar to a standard grade GPS receiver, the RTK Facet mosaic will output industry standard NMEA sentences at 4Hz and broadcast them over any paired Bluetooth® device. The end user will need to parse the NMEA sentences using commonly available mobile apps, GIS products, or embedded devices (there are many open source libraries). Unlike standard grade GPS receivers that have 2500mm accuracy, the accuracy in this mode is approximately 300mm horizontal positional accuracy.

  • w/ RTK Fix

    If the device is in Rover mode but L-Band is not available, regular RTCM based RTK is still available. When RTCM correction data is sent over Bluetooth® or into the radio port, the device will automatically enter Positioning with RTK mode. In this mode RTK Facet mosaic will receive L1/L2/L5 signals from the antenna; and correction data from a base station. The receiver will quickly (within a second) obtain an RTK float, then fix. The NMEA sentences will have increased accuracy of 10mm horizontal and 10mm vertical accuracy.

    1. The RTCM correction data is most easily obtained over the Internet using a free app on your phone (see our SW Maps (Android/iOS) or Lefebure NTRIP instructions) and sent over Bluetooth® to the RTK Facet mosaic.
    2. The RTCM correction data can also be received over an external cellular or radio link from a 2nd RTK Facet, Surveyor, Express, etc. that is setup as a base station.
  • w/ RTK L-Band Fix

    In Rover mode the RTK Facet mosaic will check if WiFi is available and update any L-Band keys needed (keys expire every 56 days). The device will automatically begin receiving and decrypting position correction data. Simultaneously, the RTK Facet mosaic will receive L1, L2, and L5 GNSS signals from the four constellations (GPS, GLONASS, Galileo, and BeiDou). The device will calculate the position based on the combination of GNSS and correction signals. The receiver will quickly (within 60 seconds) obtain an RTK float, then fix. Similar to a standard grade GPS receiver, the RTK Facet mosaic will output industry standard NMEA sentences at 4Hz and broadcast them to any paired Bluetooth® device. The end user will need to parse the NMEA sentences using commonly available mobile apps, GIS products, or embedded devices (there are many open source libraries). Unlike standard grade GPS receivers that have 2500mm accuracy, the accuracy in this mode is approximately 10 to 60mm horizontal positional accuracy.

Base Mode

In Base mode the device will enter Base Station mode. This is used when the device is mounted to a fixed position (like a tripod or roof). The RTK Facet mosaic will initiate a survey. After 60 to 120 seconds the survey will complete and the RTK Facet mosaic will begin transmitting RTCM correction data out the radio port. A base is often used in conjunction with a second RTK Facet mosaic (or RTK Surveyor, Express, Express Plus, etc) unit set to Rover to obtain the 10mm accuracy. Said differently, the Base sits still and sends correction data to the Rover; so that the Rover can calculate a really accurate position.

Connectors

RTK Facet mosaic Connectors

The SparkFun RTK Facet mosaic connectors shown with the dust cover removed.

There are a variety of connectors protected under a dust flap.

USB

RTK Facet mosaic USB-C Connector

This USB-C connector is used for four purposes:

  • Charging the device
  • Configuring the RTK Facet mosaic, and reprogramming the ESP32
  • Configuring or updating the firmware of the mosaic-X5 (as needed)

There is a USB hub built into the RTK Facet mosaic. When you attach the device to your computer it will enumerate as two COM ports.

Two COM ports from one USB device

In the image above, the USB-SERIAL CH340 is the ESP32 and the USB Serial Device is the mosaic-X5.

Tip - USB Drivers

CH340 UART Converter

The CH340 serial-to-USB converter allows users to interface with the ESP32-WROVER-E module through the USB-C connector. To utilize the CH340, users may need to install a USB driver, which can be downloaded from the manufacturer website.

Linux

A USB driver should not be required for most Linux based operating systems; the standard Linux CDC-ACM driver is usually sufficient. However, if necessary, users can try the USB driver below:

Download Page for CH341SER_LINUX.ZIP

mosaic-X5

On Windows computers, a USB driver is required to recognize and interact with the mosaic-X5 module through the USB interface.

  • Windows

    The USB driver necessary to recognize and interact with the mosaic-X5 module through the USB interface, can be installed through two methods:

    1. The driver is installed during the installation process.
    2. The installation file for the Windows USB driver will be available from the mass-storage device when the board is initially connected to the computer.
    Having Trouble?

    For users who are having trouble installing the USB driver, we have an archived version (v3.0.2) of the installation file. Users can download version 3.0.2 of the driver, by clicking on the button below.

    Download USB Driver (v3.0.2)

    Latest Driver

    This driver version was archived at the time that the mosaic-X5 hookup guide was written. Please do not request for the file to be updated.

    For the latest USB driver from Septentrio, please install their driver through the RxTools software suite.

Linux

On Linux, the standard Linux CDC-ACM driver is suitable for the mosaic-X5 module.

Configuring the RTK Facet mosaic can be done over the USB-Serial CH340 COM port via serial text menu. Various debug messages are printed to this port at 115200bps and a serial menu can be opened to configure advanced settings. The mosaic-X5 can be configured over the USB Serial Device port using web interface. It's not necessary in normal operation but is handy for tailoring the receiver to specific applications.

Radio

RTK Facet mosaic Radio Connector

This port is used when an external cellular or radio link is needed. This port is not used if you transfer RTCM from your phone to the RTK Facet mosaic over Bluetooth.

This 4-pin JST connector can be used to allow RTCM correction data to flow into the device when it is acting as a Rover or out of the device when it is acting as a Base. The connector is a 4-pin locking 1.25mm JST SMD connector (1). The RTK Facet mosaic comes with a cable to interface to this connector, but additional cables can be purchased separately. You will most likely connect one of our Serial Telemetry Radios to this port, if you don't have access to a correction source on the internet. The pinout is 3.5-5.5V/TX/RX/GND from left to right as pictured. 3.5V to 5.5V is provided by this connector to power a radio with a voltage that depends on the power source. If USB is connected to the RTK Facet mosaic then voltage on this port will be 5V (+/-10%). If running off of the internal battery then voltage on this port will vary with the battery voltage (3.5V to 4.2V depending on the state of charge). This port is capable of sourcing up to 600mA and is protected by a PTC (resettable fuse). This port should not be connected to a power source.

    • SMD board connector
      • part#: SM04B-GHS-TB
    • Mating cable connector
      • part#: GHR-04V-S

Data

RTK Facet mosaic Data Port

This port is used when an external system is connected such as a rover, car, timing equipment, camera triggers, etc. This port is not used if you transfer NMEA positional data to your phone from the RTK Facet mosaic over Bluetooth.

This 4-pin JST connector is used to output and input a variety of data to the RTK Facet mosaic. The connector is a 4-pin locking 1.25mm JST SMD connector (1). The RTK Facet mosaic comes with a cable to interface to this connector, but additional cables can be purchased separately.

    • SMD board connector
      • part#: SM04B-GHS-TB
    • Mating cable connector
      • part#: GHR-04V-S

Internally, the Data connector is connected to a digital mux allowing one of four software selectable setups. See the Ports Menu for a description of each option.:

  • NMEA - The TX pin outputs any enabled messages (NMEA and RTCM) at a default of 460800bps (configurable 9600 to 921600bps). The RX pin can receive RTCM messages for an RTK fix.
  • PPS/Trigger - The TX pin outputs the pulse-per-second signal that is accurate to 30ns RMS. The RX pin is connected to the EVENTA pin on the mosaic-X5, allowing for events to be measured with incredibly accurate nano-second resolution. Useful for things like audio triangulation.
  • I2C - The TX pin operates as SCL, RX pin as SDA on the I2C bus. This allows additional sensors to be connected to the I2C bus.
  • GPIO - The TX pin operates as a DAC capable GPIO 21 on the ESP32. The RX pin operates as a ADC capable input (GPIO39) on the ESP32. This is useful for custom applications.

Most applications do not need to utilize this port and will send the NMEA position data over Bluetooth. This port can be useful for sending position data to an embedded microcontroller or single board computer. The pinout is 3.3V/TX/RX/GND. 3.3V from left to right as pictured, which is provided by this connector to power a remote device if needed. While the port is capable of sourcing up to 600mA, we do not recommend more than 300mA. This port should not be connected to a power source.

microSD

RTK Facet mosaic microSD connector

This slot accepts standard microSD cards up to 32GB formatted for FAT32.

The following messages are supported for logging:

  • NMEA-ALM
  • NMEA-AVR
  • NMEA-DTM
  • NMEA-GBS
  • NMEA-GFA
  • NMEA-GGA
  • NMEA-GGK
  • NMEA-GGQ
  • NMEA-GLL
  • NMEA-GMP
  • NMEA-GNS
  • NMEA-GRS
  • NMEA-GSA
  • NMEA-GST
  • NMEA-GSV
  • NMEA-HDT
  • NMEA-HRP
  • NMEA-LLK
  • NMEA-LLQ
  • NMEA-RBD
  • NMEA-RBP
  • NMEA-RBV
  • NMEA-RMC
  • NMEA-ROT
  • NMEA-SNC
  • NMEA-TFM
  • NMEA-THS
  • NMEA-TXTbase
  • NMEA-VTG
  • NMEA-ZDA
  • RTCM3-1001
  • RTCM3-1002
  • RTCM3-1003
  • RTCM3-1004
  • RTCM3-1005
  • RTCM3-1006
  • RTCM3-1007
  • RTCM3-1108
  • RTCM3-1009
  • RTCM3-1010
  • RTCM3-1011
  • RTCM3-1012
  • RTCM3-1013
  • RTCM3-1019
  • RTCM3-1020
  • RTCM3-1029
  • RTCM3-1033
  • RTCM3-1042
  • RTCM3-1044
  • RTCM3-1045
  • RTCM3-1046
  • MSM1
  • MSM2
  • MSM3
  • MSM4
  • MSM5
  • MSM6
  • MSM7
  • RTCM3-1230

Qwiic

RTK Facet mosaic Qwiic connector

This 4-pin Qwiic connector exposes the I2C bus of the ESP32-WROVER-E module. Currently, there is no firmware support for adding I2C devices to the RTK Facet mosaic, but support may be added in the future.

Antenna

Internal RTK Facet mosaic Antenna

It's built in! Housed under the dome of the RTK Facet mosaic is a surveyor grade L1/L2/L-Band antenna. This antenna is a unique combination of elements designed to receive the GNSS signals (L1/L2) alongside the 1.55GHz PointPerfect corrections.

SparkFun RTK Facet mosaic Antenna Reference Point

SparkFun RTK Facet mosaic Antenna Reference Points

The built-in antenna has an antenna phase center (APC) of 69mm from the base of the device to the measuring point of the L1 antenna and an APC of 68mm to the measuring point of the L2 antenna.

Internal Battery

RTK Facet mosaic Display showing three battery bars

RTK Facet mosaic Display showing three battery bars

The RTK Facet mosaic has a built in 6000mAh battery and consumes approximately 240mA worst case with Bluetooth connection active and GNSS fully tracking. This will allow for around 25 hours of use in the field. If more time is needed in the field a standard USB power bank can be attached. If a 10,000mAh bank is attached one can estimate 56 hours of run time; assuming, 25% of the capacity is lost to efficiencies of the power bank and charge circuit within RTK Facet mosaic.

The RTK Facet mosaic can be charged from any USB port or adapter. The charge circuit is rated for 1000mA, so USB 2.0 ports will charge at 500mA and USB 3.0+ ports will charge at 1A.

To quickly view the state of charge, turn on the unit. The battery icon will indicate the following:

  • 3 bars: >75% capacity remain
  • 2 bars: >50% capacity remain
  • 1 bar: >25% capacity remain
  • 0 bars: <25% capacity remain

Display

RTK Facet mosaic Front Face

The display on the front of the RTK Facet mosaic.

The RTK Facet mosaic has a 0.96" high-contrast OLED display. While small, it packs various situational data that can be helpful in the field. Please see the SparkFun RTK Everywhere Firmware Manual for a description of the information being displayed.