Skip to content

Hardware Overview

Design Files

The SparkFun LG290P Quadband GNSS RTK breakout board's dimensions, pin layout, and connectors are exactly the same as our vary popular SparkFun GPS-RTK-SMA Breakout - ZED-F9P (Qwiic); and can be used as a drop-in replacement. The board features three UART ports, which are accessible through the USB-C connector, BlueSMiRF (6-pin PTH) header , and 4-pin locking JST connector. Users can also interface with the board through the 24 PTH pins that are broken out around the edge of the board. For the GNSS antenna, an SMA antenna connector is provided on the edge of the board; additionally, there are also SMD pads for another *(RP-)*SMA connector to output a PPS signal. We also provide two 4-pin JST Qwiic connectors for future use, when the I2 feature becomes available for the GNSS module.

USB-C Connector

The USB connector is provided to power and communicate with the LG290P GNSS receiver. For most users, it will be the primary method for interfacing with the LG290P.

USB-C Connector

USB-C connector on the Quad-band GNSS RTK breakout board.

CH342 Dual UART Converter

The CH342 serial-to-USB converter allows users to interface with the UART1 port of the LG290P GNSS module through the USB-C connector. Although the CH342 provides a dual-channel UART interface, only a single channel is utilized to communicate with the LG290P GNSS module. To utilize the CH342, users may need to install a USB driver, which can be downloaded from the manufacturer website.

Once the USB driver is installed:

  • Two virtual COM ports will be emulated, which can be used as standard COM ports to access the receiver.
  • Users should select COM port with the lower enumeration or the one labeled as Channel A.
Tip - USB Drivers

Linux

A USB driver is not required for Linux based operating systems.

Power

The Quad-band GNSS RTK breakout board only requires 3.3V to power the board's primary components. The simplest method to power the board is through the USB-C connector. Alternatively, the board can also be powered through the other connectors and PTH pins.

Power connections

Quad-band GNSS RTK breakout board's power connections.

Below, is a general summary of the power circuitry for the board:

  • 5V - The voltage from the USB-C connector, usually 5V.
    • Can be utilized as the primary power source for the entire board.
  • 3V3 - 3.3V power rail, which powers the LG290P GNSS module, backup battery, and the power LED.
    • Power can also be distributed to/from any of the 3V3 PTH pins or JST connectors (Qwiic or UART3).
      • For power that is supplied through these connections, the LG290P requires a supply voltage of 3.15–3.45V.
    • A regulated 3.3V is supplied by the RT9080, when powered from the 5V PTH pin or USB connector
      • Input Voltage Range: 3.0 to 5.5V
      • The RT9080 LDO regulator can source up to 600mA.
  • 3V3_EN - Controls the power output form the RT9080 voltage regulator.
    • By default, the pin is pulled-up to 5V and to enable the RT9080 output voltage.
  • GND - The common ground or the 0V reference for the voltage supplies.

Info

For more details, users can reference the schematic and the datasheets of the individual components on the board.

  • Power Consumption

    The power consumption of the LG290P GNSS module depends on the GNSS signals enabled and the positioning mode.

    Current Consumption:

    • Acquisition: 91mA (300.3mW)
    • Tracking: 91mA (300.3mW)
    • Backup Mode: 12μA (39.6mW)

  • Backup Battery

    While charged, the backup battery allows the GNSS module to hot/warm start with valid ephemeris data (time and GNSS orbital trajectories) that was stored.

    Time to First Fix:

    • Cold Start: 28s
    • Warm Start: 28s
    • Hot Start: 1.7s

  LG290P GNSS

The centerpiece of the Quad-band GNSS RTK breakout board, is the LG290P GNSS module from Quectel. The LG290P is a low-power, multi-band, multi-constellation GNSS receiver capable of delivering centimeter-level precision at high update rates. The built-in NIC anti-jamming unit provides professional-grade interference signal detection and elimination algorithms, which effectively mitigate against multiple narrow-band interference sources and significantly improves the signal reception performance in complex electromagnetic environments. With its performance advantages of high-precision and power consumption, this board is an ideal choice for high-precision navigation applications, such as intelligent robots, UAVs, precision agriculture, mining, surveying, and autonomous navigation.

LG290P GNSS module

The LG290P module on the Quad-band GNSS RTK breakout board.

QR code to product video

General Features
  • Supply Voltage: 3.15–3.45V
  • Tracking Channels: 1040
  • Concurrent signal reception: 5 + QZSS
    • L1, L2, L5, E6 frequency bands
  • Sensitivity:
    • Acquisition: -146dBm
    • Tracking: -160dBm
    • Reacquisition: -155dBm
  • Antenna Power: External or Internal
  • GNSS Constellations and SBAS Systems:
    • USA: GPS + WASS
    • Russia: GLONASS + SDCM
    • EU: Galileo + EGNOS
    • China: BDS + BDSDAS
    • Japan: QZSS + MSAS
    • India: NavIC + GAGAN
  • Accuracy of 1PPS Signal: 5ns (RMS)
  • Update Rate:
    • Default: 10Hz
    • Max: 20Hz
  • Time to First Fix (without AGNSS):
    • Cold Start: 28s
    • Warm Start: 28s
    • Hot Start: 1.7s
  • RTK Convergence Time: 5s
  • Dynamic Performance:
    • Maximum Altitude: 10000m
    • Maximum Velocity: 490m/s
    • Maximum Acceleration: 4g
  • Built-in NIC anti-jamming unit
  • Interfaces
    • UART (x3)
      • Baud Rate: 9600–3000000bps
        • Default: 460800bps
      • Protocol: NMEA 0183/RTCM 3.x
    • SPI1 (x1)
    • I2C1 (x1)
  • Operating temperature: -40°C to +85°C
  • Footprint: 12.2mm × 16mm × 2.6mm
  • Weight: ~0.9g
Supported Frequency Bands

The LG290P modules are multi-band, multi-constellation GNSS receivers. Below, is a chart illustrating the frequency bands utilized by all the global navigation satellite systems; along with a list of the frequency bands and GNSS systems supported by the LG290P GNSS module.

GNSS frequency bands
Frequency bands of the global navigation satellite systems. (Source: Tallysman)

Supported Frequency Bands:

  • GPS: L1 C/A, L1C2, L5, L2C
  • GLONASS: L1, L2
  • Galileo: E1, E5a, E5b, E6
  • BDS: B1I, B1C, B2a, B2b, B2I, B3I
  • QZSS: L1 C/A, L1C2, L5, L2C
  • NavIC: L5
  • SBAS: L1 C/A
  • L-band PPP3:
    • PPP: B2b
    • QZSS: L6
    • Galileo HAS: E6

Supported GNSS Constellations:

  • GPS (USA)
  • GLONASS (Russia)
  • Galileo (EU)
  • BDS (China)
  • QZSS (Japan)
  • NavIC (India)

Supported SBAS Systems:

  • WASS (USA)
  • SDCM (Russia)
  • EGNOS (EU)
  • BDSBAS (China)
  • MSAS (Japan)
  • GAGAN (India)

Info

For a comparison of the frequency bands supported by the LG290P GNSS modules, refer to sections 1.2, 1.5, and 1.6 of the hardware design manual.

What are Frequency Bands?

A frequency band is a section of the electromagnetic spectrum, usually denoted by the range of its upper and lower limits. In the radio spectrum, these frequency bands are usually regulated by region, often through a government entity. This regulation prevents the interference of RF communication; and often includes major penalties for any interference with critical infrastructure systems and emergency services.

GNSS frequency bands
Frequency bands of the global navigation satellite systems. (Source: ESA)

However, if the various GNSS constellations share similar frequency bands, then how do they avoid interfering with one another? Without going too far into detail, the image above helps illustrate some of the characteristics, specific to the frequency bands of each system. With these characteristics in mind, along with other factors, the chart can help users to visualize how multiple GNSS constellations might co-exist with each other.

For more information, users may find these articles of interest:

GNSS Accuracy

The accuracy of the position reported from the LG290P GNSS module, can be improved based upon the correction method being employed. Currently, RTK corrections provide the highest level of accuracy; however, users should be aware of certain limitations of the system:

  • RTK technique requires real-time correction data from a reference station or network of base stations.
    • RTK corrections usually come from RTCM messages that are signal specific (i.e. an RTK network may only provide corrections for specific signals; only E5b and not E5a).
  • The range of the base stations will vary based upon the method used to transmit the correction data.
  • The reliability of RTK corrections are inherently reduced in multipath environments.

Correction Method Horizontal Vertical Velocity
Standalone 0.7m
~2.3'		 2.5m
~8.2'		 3cm/s (0.108kph)
~1.2in/s (0.067mph)
RTK 0.8cm (+1ppm)
~0.3"		 1.5cm (+1ppm)
~.6"

RTK Corrections

To understand how RTK works, users will need a more fundamental understanding of the signal error sources.

Peripherals and I/O Pins

The LG290P GNSS features several peripheral interfaces and I/O pins. Some of these are broken out as pins on the Quad-band GNSS RTK breakout board; whereas, others are broken out to their specific interface (i.e. USB connector, JST connector, etc.). Additionally, some of their connections are tied to other components on the board.

Peripherals interfaces

The peripheral interfaces and I/O pins on the Quad-band GNSS RTK breakout board.

Interfaces:

  • UART (x3)
  • SPI1
  • I2C1
  • Event Trigger4
  • Timing Signal
  • RTK Signal
  • Module Reset

The LG290P GNSS has three UART ports, which can be operated and configured separately.

UART interface
The UART ports on the Quad-band GNSS RTK breakout board.

Default Configuration

By default, the UART ports are configured with the following settings:

  • Logic Level: 3.3V
  • Baudrate: 460800bps
  • Data Bits: 8
  • Parity: No
  • Stop Bits: 1
  • Flow Control: None
  • Protocols:
    • NMEA 0183
    • RTCM 3.x
Pin Connections

When connecting to the board's UART pins to another device, the pins should be connected based upon the flow of their data.

Board RX TX GND
UART Device TX RX GND

UART1 can only be accessed from the USB-C connector, through the CH342 serial-to-USB converter. For Windows and MacOS computers (1), a USB driver must be installed in order to communicate with the LG290P module through the CH342 converter. Once the USB driver is installed:

  • Two virtual COM ports are emulated, which can be used as standard COM ports to access the receiver.
  • Users should select COM port with the lower enumeration or listed as Channel A.
  1. On Linux, the standard Linux CDC-ACM driver is suitable.

UART2 is available through the breakout PTH pins or the BlueSMiRF header pins. The pin layout of the BlueSMiRF header is pin compatible with many of our serial devices (i.e. UART adapters, serial data loggers, BlueSMiRF transceivers).

UART3 is available through the breakout PTH pins or the locking JST connector. The pin layout of the 4-pin locking JST connector is compatible with many of our serial radios and adapter cables.

UART Protocols

UART Protocols

By default, the UART ports are configured to transmit and receive NMEA 0183 and/or RTCM 3.x messages. These messages are generally used for transmitting PNT data; and providing or receiving RTK corrections, respectively. Quectel also implements a system of proprietary messages (PQTM) for users to configure the LG290P, following the data format of the NMEA protocol. The expected structure of these proprietary messages is shown below:

NMEA data structure
The data structure of Quectel messages for the NMEA protocol.

A full list of compatible NMEA 0183 v4.11 messages, is provided in section 2.2. Standard Messages of the GNSS Protocol Specification manual. This protocol is used for outputting GNSS data, as detailed by the National Marine Electronics Association organization.

List of Standard NMEA Messages

Message Type Mode Message Description
RMC Output Recommended Minimum Specific GNSS Data
GGA Output Global Positioning System Fix Data
GSV Output GNSS Satellites in View
GSA Output GNSS DOP and Active Satellites
VTG Output Course Over Ground & Ground Speed
GLL Output Geographic Position – Latitude/Longitude

A full list of PQTM messages (proprietary NMEA messages defined by Quectel) supported by LG290P, is provided in section 2.3. PQTM Messages of the GNSS Protocol Specification manual. This protocol is used to configure or read the settings for the LG290P GNSS module.

List of Proprietary Quectel Messages

Message Type Mode Message Description
PQTMVER Output Outputs the firmware version
PQTMCOLD Input Performs a cold start
PQTMWARM Input Performs a warm start
PQTMHOT Input Performs a hot start
PQTMSRR Input Performs a system reset and reboots the receiver
PQTMUNIQID Output Queries the module unique ID
PQTMSAVEPAR Input Saves the configurations into NVM
PQTMRESTOREPAR Input Restores the parameters configured by all commands to their default values
PQTMVERNO Output Queries the firmware version
PQTMCFGUART Input/Output Sets/gets the UART interface
PQTMCFGPPS Input/Output Sets/gets the PPS feature
PQTMCFGPROT Input/Output Sets/gets the input and output protocol for a specified port
PQTMCFGNMEADP Input/Output Sets/gets the decimal places of standard NMEA messages
PQTMEPE Output Outputs the estimated position error
PQTMCFGMSGRATE Input/Output Sets/gets the message output rate on the current interface
PQTMVEL Output Outputs the velocity information
PQTMCFGGEOFENCE Input/Output Sets/gets geofence feature
PQTMGEOFENCESTATUS Output Outputs the geofence status
PQTMGNSSSTART Input Starts GNSS engine
PQTMGNSSSTOP Input Stops GNSS engine
PQTMTXT Output Outputs short text messages
PQTMCFGSVIN Input/Output Sets/gets the Survey-in feature
PQTMSVINSTATUS Output Outputs the Survey-in status
PQTMPVT Output Outputs the PVT (GNSS only) result
PQTMCFGRCVRMODE Input/Output Sets/gets the receiver working mode
PQTMDEBUGON Input Enables debug log output
PQTMDEBUGOFF Input Disables debug log output
PQTMCFGFIXRATE Input/Output Sets/gets the fix interval
PQTMCFGRTK Input/Output Sets/gets the RTK mode
PQTMCFGCNST Input/Output Sets/gets the constellation configuration
PQTMDOP Output Outputs dilution of precision
PQTMPL Output Outputs protection level information
PQTMCFGODO Input/Output Sets/gets the odometer feature
PQTMRESETODO Input Resets the accumulated distance recorded by the odometer
PQTMODO Output Outputs the odometer information
PQTMCFGSIGNAL Input/Output Sets/gets GNSS signal mask
PQTMCFGSAT Input/Output Sets/gets GNSS satellite mask
PQTMCFGRSID Input/Output Sets/gets the reference station ID
PQTMCFGRTCM Input/Output Sets/gets RTCM

A full list of compatible RTCM v3 messages, is provided in section 3. RTCM Protocol of the GNSS Protocol Specification manual. This protocol is used for transferring GNSS raw measurement data, as detailed by the Radio Technical Commission for Maritime Services organization.

List of Supported RTCMv3 (MSM) Messages

Message Type Mode Message Description
1005 Input/Output Stationary RTK Reference Station ARP
1006 Input/Output Stationary RTK Reference Station ARP with height
1019 Input/Output GPS Ephemerides
1020 Input/Output GLONASS Ephemerides
1041 Input/Output NavIC/IRNSS Ephemerides
1042 Input/Output BDS Satellite Ephemeris Data
1044 Input/Output QZSS Ephemerides
1046 Input/Output Galileo I/NAV Satellite Ephemeris Data
1073 Input/Output GPS MSM3
1074 Input/Output GPS MSM4
1075 Input/Output GPS MSM5
1076 Input/Output GPS MSM6
1077 Input/Output GPS MSM7
1083 Input/Output GLONASS MSM3
1084 Input/Output GLONASS MSM4
1085 Input/Output GLONASS MSM5
1086 Input/Output GLONASS MSM6
1087 Input/Output GLONASS MSM7
1093 Input/Output Galileo MSM3
1094 Input/Output Galileo MSM4
1095 Input/Output Galileo MSM5
1096 Input/Output Galileo MSM6
1097 Input/Output Galileo MSM7
1113 Input/Output QZSS MSM3
1114 Input/Output QZSS MSM4
1115 Input/Output QZSS MSM5
1116 Input/Output QZSS MSM6
1117 Input/Output QZSS MSM7
1123 Input/Output BDS MSM3
1124 Input/Output BDS MSM4
1125 Input/Output BDS MSM5
1126 Input/Output BDS MSM6
1127 Input/Output BDS MSM7
1133 Input/Output NavIC/IRNSS MSM3
1134 Input/Output NavIC/IRNSS MSM4
1135 Input/Output NavIC/IRNSS MSM5
1136 Input/Output NavIC/IRNSS MSM6
1137 Input/Output NavIC/IRNSS MSM7

From the module, the PPS output signal is a 3.3V signal output that can be access through the SMA connector and/or the PPS PTH pin. The signal is also connected to the PPS LED, which can be used as a visual indicator for its operation.

I/O for PPS signal
The timing signal's outputs on the Tri-band GNSS RTK breakout board.

Jumpers

See the Jumpers section for more details.

  • There is a jumper attached to the PPS PTH pin. When cut, it disconnects the pin from the PPS signal.
  • There is a jumper attached to the PPS LED. For low power applications, the jumper can be cut to disable the PPS LED.
Use Case
  • Users could use this signal in conjunction with the event pins to synchronize two modules with each other.
  • Users could use this signal to create their own Stratum 0 source for the NTP on a primary time server.

The RTK PTH pin operates as both the RTK_STAT status indicator for the RTK positioning and ANT_ON power control for the external LNA or active antenna power. The pin is also connected to the RTK LED, which can be used as a visual indicator for its operation.

I/O for RTK signal
The RTK signal's outputs on the Tri-band GNSS RTK breakout board.

In this configuration, the pin is set to a high level at startup.

  1. If the pin output is high, it indicates the module has entered the RTK fixed mode.
  2. If the pin output is low, it indicates that the module exited the RTK fixed mode.
  3. If the pin outputs an alternating pin level, it indicates that the module received the correct RTCM data and did not enter the RTK fixed mode.

In this configuration, the pin is used to control the external LNA or active antenna power supply.

  • When the pin is high, the antenna is powered.
  • When the pin is low, the antenna is not powered.
Jumpers

See the Jumpers section for more details.

  • There is a jumper attached to the RTK LED. For low power applications, the jumper can be cut to disable the RTK LED.

The RST pin can be used to reset the LG290P module if it enters an abnormal state. To reset the GNSS module, the pin must be low for more than 100ms.

Reset Pin
The RST pin on the Tri-band GNSS RTK breakout board.

SMA Connectors

While there are two SMD pads for SMA connectors, only the antenna's SMA connector is populated on the Quad-band GNSS RTK breakout board. The Antenna L1/2/5/6 connector is an input for the GNSS antenna. Whereas, the PPS SMD pad provides a output for the PPS timing signal.

SMA Connector

The SMA connector for an external GNSS antenna on the Quad-band GNSS RTK breakout board.

SMD Pads

The SMD pads to add an SMA connector for the PPS output from the Tri-band GNSS RTK breakout board.

Antenna Specifications

  • Passive antennas are not recommended for the LG290P GNSS module.
  • To mitigate the impact of out-of-band signals, utilize an active antenna whose SAW filter is placed in front of the LNA in the internal framework.
    • DO NOT select and antenna with the LNA placed in the front.
  • There is no need to inject an external DC voltage into the SMA connector for the GNSS antenna. Power is already provided from the LG290P module for the LNA of an active antenna.

JST Connector

The Quad-band GNSS RTK breakout features a 4-pin JST GH connector, which is polarized and locking. Users can access the pins of the UART3 port, through the JST connector with our breadboard cable(1) or through the PTH pins. The pin layout of the JST connector is compatible with many of our serial radios and adapter cables.

  1. Product Thumbnail

    Breadboard to JST-GHR-04V Cable - 4-Pin x 1.25mm Pitch
    CAB-17240

JST connector

The JST connector on the Quad-band GNSS RTK breakout board.

Pin Connections

Pin Connections

When connecting the Quad-band GNSS RTK breakout board to other products, users need to be aware of the pin connections between the devices.

Pin Number 1
(Left Side) 		2 3 4
Label VCC TX3 RX3 GND
Function Voltage Output
- Default: 3.3V
- Selectable: 3.3V or 5V 		UART3 - Receive UART3 - Transmit Ground

When connecting the Quad-band GNSS RTK breakout board to our radios, the pin connections should follow the table below. If the flow control is not enabled, the only the RX, TX, and GND pins are utilized.

Board RX TX GND
Radio TX RX GND

As documented in the LoRaSerial product manual, the pin connections between a host system (i.e. Quad-band GNSS RTK breakout board) and the LoRaSerial Kit radio is outlined in the image below.

Flow Control
The COM ports on the Quad-band GNSS RTK breakout board.

BlueSMiRF Header

The Quad-band GNSS RTK breakout features a 6-pin BlueSMiRF PTH header for UART2. The pin layout of which, is compatible with many of our serial devices (i.e. UART adapters, serial data loggers, BlueSMiRF transceivers).

BlueSMiRF header

The 6-pin BlueSMiRF PTH header on the Quad-band GNSS RTK breakout board.

Pin Connections

Pin Connections

When connecting the Quad-band GNSS RTK breakout board to other products, users need to be aware of the pin connections between the devices.

Pin Number 1
(Left Side) 		2 3 4 5 6
Label TX2 RX2 3V3 GND
Function UART2 - Receive UART2 - Transmit 3.3V Ground

Status LEDs

There are three status LEDs on the Quad-band GNSS RTK breakout board:

Status LEDs

The status LED indicators on the Quad-band GNSS RTK breakout board.

  • PWR - Power (Red)
    • Turns on once 3.3V power is supplied to the board
  • PPS - Pulse-Per-Second (Yellow)
    • Indicates when there is a pulse-per-second signal (see the PPS Output section)
  • RTK - RTK Mode (White)
    • Indicates when an RTK fix has been established or when the correct RTCM data is being received (see the RTK section)

Jumpers

Never modified a jumper before?

Check out our Jumper Pads and PCB Traces tutorial for a quick introduction!

There are seven jumpers on the back of the board that can be used to easily modify the hardware connections on the board. From which, there are three jumpers that control power to the status LEDs on the board. By default, all the jumpers are connected, to power the status LEDs. For low power applications, users can cut the jumpers to disconnect power from each of the LEDs.

Jumpers

The jumpers on the back of the Quad-band GNSS RTK breakout board.

  • VSEL - This jumper can be modified to configure/disconnect the VCC pin of the 4-pin locking JST connector to/from 3V3 or 5V power.
  • BT_VCC - This jumper can be cut to disconnect the 3V3 BlueSMiRF header pin from the 3.3V output of the RT9080 LDO regulator.
  • PWR - This jumper can be cut to remove power from the red, power LED.
  • PPS - This jumper can be cut to remove power from the yellow LED, which is connected to the PPS signal.
  • RTK - This jumper can be cut to remove power from the white LED, indicating RTK fix or operation in RTK mode.
  • PPS-DC - This jumper can be cut to disconnect the pulse per second signal from the PTH pin.
  • SHLD - This jumper can be cut to disconnect the shielding of the USB-C connector from the GND plane of the board

Info

By default, PPS signal is connected to the PPS pin.

  1. Feature Under Development

    Currently, only the UART interface is supported by the module. Support for the I2C and SPI interfaces are still under development.

    ↩↩↩↩

  2. Feature Under Development

    Support for the L1C frequency band has not been implemented.

    ↩↩

  3. Feature Under Development

    Corrections for some of the PPP services have not been implemented.

    ↩

  4. Feature Under Development

    The event trigger has not been implemented.

    ↩