Skip to content

Hardware Overview

Design Files

  • Design Files

  • Manipulate 3D Model
    Controls Mouse Touchscreen
    Zoom Scroll Wheel 2-Finger Pinch
    Rotate Left-Click & Drag 1-Finger Drag
    Move/Translate Right-Click & Drag 2-Finger Drag

    Board Dimensions
    Dimensions of the ZED-X20P GNSS breakout board.

    Need more measurements?

    For more information about the board's dimensions, users can download the KiCad files for this board. These files can be opened in KiCad and additional measurements can be made with the measuring tool.

    KiCad - Free Download!

    KiCad is free, open-source CAD program for electronics. Click on the button below to download their software. (*Users can find out more information about KiCad from their website.)

    📏 Measuring Tool

    This video demonstrates how to utilize the dimensions tool in KiCad, to include additional measurements:

    QR code to play video

Board Layout

The SparkFun Allband GNSS RTK Breakout - ZED-X20P (Qwiic) features the following:

Layout

Layout of the major components on the breakout board.

  1. USB-C Connector
    The primary inteface for powering and interacting with the board
  2. ZED-X20P GNSS Module
    The u-blox ZED-X20P GNSS module
  3. Header Pins
    Exposes pins to power the board and breaks out the interfaces of the ZED-X20P GNSS module
  4. BlueSMiRF Header Pins
    Exposes the UART2 interface of the ZED-X20P GNSS module
  5. JST Connector
    Exposes the UART2 interface of the ZED-X20P GNSS module
  6. Qwiic Connectors
    Exposes the I2C interface of the ZED-X20P GNSS module
  7. Status LEDs
    LED status indicators for the ZED-X20P GNSS module
  8. Antenna L1/2/5/6 RF Connectors
    SMA and U.FL (optional) connectors for an external GNSS antenna

USB-C Connector

A USB connector is provided to power the board and interface with the ZED-X20P GNSS receiver. For most users, it will be the primary method for communicating with the ZED-X20P module.

USB-C Connector

USB-C connector on the ZED-X20P GNSS breakout board.

Power

The simplest method to power the board is through the USB-C connector. However, the ZED-X20P GNSS breakout board only requires 3.3V to power most of its components(1), which can be supplied though JST connector, Qwiic connector, or PTH pins.

  1. 5V is only required to utilize the USB interface; and when enabled, it can also power the JST connector.

Power connections

ZED-X20P GNSS breakout board's power connections.

Below, is a general summary of the power circuitry on the board; most are broken out as PTH pins:

  • VIN - The voltage from the USB-C connector, usually 5V.
    • Input Voltage Range: 1.2 - 5.5V (1)
    • Power source for the entire board
      • Powers the 3.3V voltage regulator (RT9080), which can source up to 600mA
      • When enabled, it can also power the BlueSMiRF header
  • 3V3 - Provides a regulated 3.3V from the RT9080, using the power supplied from the VIN pin or USB-C connector.
  • EN - Enables the voltage output from the RT9080, 3.3V voltage regulator
    • Enabled by default (active HIGH)
  • RST - Used to reset the ZED-X20P GNSS module
    • Connected to the RESET_N pin of the ZED-X20P module, an input-only pin with an internal pull-up resistor (2)
    • Driving the pin LOW for at least 1ms triggers a cold-start reset, clearing the BBR content (receiver configuration, real-time clock (RTC), and GNSS orbit data)
  • GND - The common ground or the 0V reference for the voltage supplies.
  • Backup Battery - Provides backup power to the ZED-X20P GNSS module to maintain ephemeris data for warm starts

  1. While the RT9080 LDO regulator has an input voltage range of 1.2 - 5.5V, a minimum supply voltage of 3.5V is recommended for a 3.3V output.

  2. No capacitors should be placed between RESET_N to GND, otherwise it could trigger a reset on every startup.

JST Connector

The VSEL pin of the BlueSMiRF header is designed to operate as a voltage output. However, an input voltage can be supplied through the pin, but users should be mindful of any voltage contention issues.

Additionally, the jumper for the VSEL pin can be modified to change to output voltage level.

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 ZED-X20P module depends on the GNSS signals enabled and if the module is acquiring or tacking those signals. The table below, lists the average current consumption with a supply voltage of 3.3V.

GNSS Signals Acquisition Tracking
GPS+GAL+BDS 75mA 70mA
GPS 50mA 50mA

Tip

During acquisition, the current consumption may reach up to 85mA; make sure the primary power source can sustain this.

Info

For more information, please refer to the ZED-X20P Datasheet.

ZED-X20P GNSS Receiver

The centerpiece of this GNSS breakout board is the ZED-X20P module from u-blox; it features their latest X20 GNSS engine, a successor to their popular F9 engine. The ZED-X20P module is an all-band, high precision GNSS receiver that concurrently processes signals from the GPS, Galileo, BeiDou, QZSS, and NavIC constellations across all GNSS frequency bands, including L-band. With positioning algorithms for Real-time Kinematics (RTK), PPP-RTK, and Precise Point Positioning* (PPP) technologies, the module supports standard RTCM corrections for Virtual Reference Stations (VRS) in a Network RTK setup or a local base station setup. Additionally, L-band correction services are natively supported without the need to integrate an external receiver, such as the NEO-D9S.

With its very high update rate, the ZED-X20P module is ideal for control applications, ensuring smooth and reliable operation. The module also protects system integrity with multi-layered defenses, including a Root of Trust, jamming and spoofing detection, cryptographic authentication of navigation messages through Galileo OSNMA, and more. The module also accommodates users with a diverse choice of interfaces including USB, UART, SPI, and I2C.

Note

*: Feature in development

ZED-X20P module

The ZED-X20P module on the breakout board.

QR code to play video

ublox engine

The frequency bands supported by the various u-blox GNSS engines.

Features:

  • Supply voltage: 2.7V to 3.6V
  • GNSS Constellations:
    • GPS (USA)
    • Galileo (EU)
    • BDS (China)
    • QZSS (Japan)
    • NavIC (India)
  • SBAS Systems:
    • WASS (USA)
    • EGNOS (EU)
    • BDSBAS (China)
    • MSAS (Japan)
    • GAGAN (India)
  • Sensitivity
    • Tracking and Nav.: -167dBm
    • Reacquisition: -160dBm
    • Cold start: -148dBm
    • Hot start: -157dBm
  • Accuracy
    • Dynamic
      • Velocity: 0.05m/s
      • Heading: 0.3°
    • Static/Position (GPS+GAL+BDS)
      • Horizontal position accuracy (CEP)
        • PVT: 1.2m
        • SBAS: 0.6m
        • RTK: 0.01m + 1ppm
        • SPARTN: <0.06m
      • Vertical position accuracy (Median)
        • PVT: 2.0m
        • SBAS: 1.0m
        • RTK: 0.01m + 1ppm
        • SPARTN: <0.10 m


  • Operational limits
    • Dynamics: <4g
    • Altitude: 80,000m
    • Velocity: 500m/s
    • Update Rate: Up to 25Hz
  • Time to Fix
    • Cold Start: < 27s
    • Aided Start: < 2s
    • Hot Start: 2s
  • Convergence time:
    • RTK: < 10s
    • SPARTN: < 50s
  • Features
    • Programmable flash memory
    • Carrier phase output
    • Jamming detection
    • Galileo OSNMA
    • Secure boot
  • Interfaces:
    • USB
    • UART x2
    • SPI
    • I2C
    • Digital I/O
      • TIMEPULSE configurable: 0.25 - 10MHz
      • EXTINT input for Wakeup
  • Services:
    • AssistNow
    • PointPerfect
  • Operating temperature: -40°C to 85°C
  • Dimensions: 17.0mm x 22.0mm x 2.4mm

Frequency Bands

The ZED-X20P module is an all-band, high precision GNSS receiver that concurrently processes signals from the GPS, Galileo, BeiDou, QZSS, and NavIC constellations across all GNSS frequency bands, including L-band. Below, are the frequency bands provided by all the global navigation satellite systems and the ones supported by the ZED-X20P module.

Supported frequency bands

The frequency bands supported by the ZED-X20P GNSS receiver.

Constellation Frequency Bands
GPS L1C/A, L2C, L5
QZSS L1C/A, L1C/B*, L2C, L5, L6
GAL E1B/C, E5a, E6
BDS B1I, B1C, B2a, B3I
NavIC L1*, L5
SBAS L1C/A

The supported frequency bands, organized by constellation.

Note

*: Feature in development

GNSS frequency bands

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

Configuration Settings

Each GNSS constellations and their signal bands can be enabled or disabled independently, using keys from the CFG-SIGNAL-* configuration group; except for the QZSS and SBAS constellation. A GNSS constellation is considered to be enabled when the constellation enable key is set and at least one of the constellation's band keys is enabled. However, the ZED-X20P only supports certain combinations of constellations and bands. For all GNSS constellations, the L1 band is mandatory even in combination with another frequency band. Any unsupported combinations will be rejected with a UBX-ACK-NAK and the warning: inv sig cfg will be sent via UBX-INF and NMEA-TXT messages (if enabled).

Supported Combinations
Constellation key
CFG-SIGNAL-GAL_ENA		 Band key
CFG-SIGNAL-GAL_E1_ENA		 Band key
CFG-SIGNAL-GAL_E5A_ENA		 Band key
CFG-SIGNAL-GAL_E6_ENA		 Constellation enabled?
true (1) true (1) true (1) true (1) yes
true (1) true (1) true (1) false (0) yes
true (1) true (1) false (0) true (1) yes
true (1) true (1) false (0) false (0) yes
true (1) false (0) true (1) true (1) no
true (1) false (0) false (0) true (1) no
true (1) false (0) true (1) false (0) no
true (1) false (0) false (0) false (0) no
false (0) true (1) true (1) true (1) no
false (0) true (1) true (1) false (0) no
false (0) true (1) false (0) true (1) no
false (0) false (0) true (1) true (1) no
false (0) false (0) false (0) true (1) no
false (0) false (0) true (1) false (0) no
false (0) true (1) false (0) false (0) no
false (0) false (0) false (0) false (0) no
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 illustrates the frequency bands of each system with a few characteristics specific to their signals. Wit 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:

Peripherals and I/O Pins

The ZED-X20P module has twenty-one I/O pins, of which eight are programmable. Most of these are broken out as PTH pins on the ZED-X20P GNSS breakout board; whereas, others are broken out to their specific interface (i.e. USB connector, jumper, U.FL connector, etc.). Additionally, some of the I/O connections are broken out with multiple components or interfaces.

Header pins

The header pins on the ZED-X20P GNSS breakout board.

Interfaces:

  • USB
  • UART x2
  • SPI
  • I2C
    • Address (7-bit): 0x42 (1000010)
  • 1x Antenna Detect (1)
  • 1x Antenna Short (2)
  • 1x Antenna Off (3)
  • 1x External interrupt
  • 1x PPS output signal
  • 1x TX Ready
  • 1x RTK Stat
  • 1x Geo Stat
  • 1x D_Sel pin
  • 1x Safe boot pin
  • 1x Reset pin
  1. Not available on the ZED-X20P GNSS breakout board.
  2. Not available on the ZED-X20P GNSS breakout board.
  3. Not available on the ZED-X20P GNSS breakout board.

The ZED-X20P has two UART interfaces that can be accessed either through the PTH pins. The UART2 interface can also be accessed through the BlueSMiRF header and the JST connector.

UART connections
The UART interfaces on the ZED-X20P GNSS breakout board.

Warning

Firmware updates can only be performed with the UART1 interface.

Tip

The UART RX interface will be disabled when more than 100 frame errors are detected during a one-second period. This can happen if the wrong baud rate is used or the UART RX pin is grounded. An error message appears when the UART RX interface is reenabled at the end of the one-second period.

Supported Protocols

The UART interface supports the following protocols:

  • Input messages: NMEA (GGA, GLL, GSA, GSV, RMC, VTG, and TXT), RTCM, SPARTN, and UBX
  • Output messages: NMEA, RTCM, and UBX

Configuration Settings

The UART interfaces can be configured with the CFG-UART* messages, but will initially have the following settings:

  • Baudrate: 4800 to 8000000bps (Default: 38400bps)
  • Data Bits: 8
  • Parity: No
  • Stop Bits: 1
  • Flow Control: None
  • UART1 Output
    • NMEA protocol with GGA, GLL, GSA, GSV, RMC, VTG, TXT messages are output by default.
    • UBX and RTCM 3.4 protocols are enabled by default, but no output messages are enabled by default.
  • UART1 Input
    • UBX, NMEA and RTCM 3.4 input protocols are enabled by default.
  • UART2 Output
    • RTCM 3.4 protocol is enabled by default, but no output messages are enabled by default.
    • NMEA protocol is disabled by default.
  • UART2 Input
    • NMEA, RTCM 3.4, and SPARTN protocols are enabled by default.

The ZED-X20P has a single I2C interface that can be accessed either through the PTH pins or the Qwiic connector.

I2C connections
The I2C connections on the ZED-X20P GNSS breakout board.

Info

For users interested in the specific details about the read and write access for th I2C bus, please refer to the ZED-X20P integration manual

What is Qwiic?

Qwiic Logo - light theme Qwiic Logo - dark theme

The Qwiic connect system is a solderless, polarized connection system that allows users to seamlessly daisy chain I2C boards together. Play the video below to learn more about the Qwiic connect system or click on the banner above to learn more about Qwiic products.

Features of the Qwiic System

no soldering - light theme no soldering - dark theme

Qwiic cables (4-pin JST) plug easily from development boards to sensors, shields, accessory boards and more, making easy work of setting up a new prototype.

polarized connector - light theme polarized connector - dark theme

There's no need to worry about accidentally swapping the SDA and SCL wires on your breadboard. The Qwiic connector is polarized so you know you’ll have it wired correctly every time, right from the start.

The PCB connector is part number SM04B-SRSS (Datasheet) or equivalent. The mating connector used on cables is part number SHR04V-S-B or an equivalent (1mm pitch, 4-pin JST connector).

daisy chainable - light theme daisy chainable - dark theme

It’s time to leverage the power of the I2C bus! Most Qwiic boards will have two or more connectors on them, allowing multiple devices to be connected.

SPI I/O pins
The SPI pins on the ZED-X20P GNSS breakout board.

The ZED-X20P has a single SPI interface that can be accessed through the PTH pins. To enable the SPI interface, users must modify the SPI jumper.

Labels SPI Pins
TX1 SDO
RX1 SDI
SDA CS
SCL CLK

The ZED-X20P module features five programmable I/O pins, but the LNA enable pin is not broken out on this board. All the inputs have internal pull-up resistors in normal operation and can be left open if unused.

LED Indicators

The PPS, RTK, and FENCE programmable I/O pins are also used as LED indicators.

LED I/O pins
The signal pins for the LED indicators on the ZED-X20P GNSS breakout board.

Disable LEDs

There are jumper attached to the LEDs of the PPS, RTK, and FENCE pins. For low power applications, users can cut the jumper to disable the LED.

  • FENCE

    The GEOFENCE_STAT signal indicates the current geofence status as to whether the receiver is inside any of the active areas. It is possible to configure up to four circular areas as geofence locations. Once configured, the receiver continuously compares its current position with the preset geofenced areas.

    The receiver toggles the assigned pin according to the combined geofence state.

    • Inside - The position is inside the geofence with the configured confidence level
    • Outside - The position lies outside of the geofence with the configured confidence level
    • Unknown - There is no valid position solution or the position uncertainty does not allow for unambiguous state evaluation

    Pin State

    • HIGH - The GEOFENCE_STAT pin is always set to high level when the combined geofence state is unknown
    • Low - A low level can represent either an inside or outside state based upon the CFG-GEOFENCE-PINPOL configuration
  • RTK

    The RTK_STAT signal indicates the RTK positioning status and if a stream of valid correction messages is being received.

    Pin State

    • LOW - Indicates that RTK fixed mode has been achieved
    • Blinking - Indicates that a valid stream of correction messages is being received and utilized, but no RTK fixed mode has been achieved
    • HIGH - Indicates that no carrier phase solution is available
  • PPS
    The PPS pin is connected to the module's time pulse (TIMEPULSE) signal and the PPS LED, as a visual indicator. The period, length, and polarity (rising or falling edge) of the TIMEPULSE signal can be configured with the CFG-TP-* messages.

Event I/O pin
The EVENT pin on the ZED-X20P GNSS breakout board.

  • EVENT
    ZED-X20P supports external interrupts through its EXTINT pin. This is useful for waking the module up from its standby mode or for timing applications.

Reset I/O pin
The RST pin on the ZED-X20P GNSS breakout board.

  • RST

    The RSTpin is connected to the RESET_N pin of the ZED-X20P module. Driving the pin LOW for at least 1ms triggers a cold-start reset, clearing the BBR content (receiver configuration, real-time clock (RTC), and GNSS orbit data).

    Info

    Capacitors should not be placed between RST and GND; otherwise, it could trigger a reset on startup.

  • D_SEL

    The D_SEL pin can be used to configure the functionality of the combined UART1, I2C, and SPI interfaces. It is available as the SPI jumper on the back of the board.

    Info

    When pulled LOW (by closing the jumper), the D_SEL enables the SPI interface on the UART1 and I2C pins.

Note

The SAFEBOOT_N test point is for updates and reconfiguration. The ZED-X20P module will enter safeboot mode, if this pin is pulled LOW at starup.

The SAFEBOOT_N and TIMEPULSE (PPS) pins are internally connected in the ZED-X20P module, by a 1 kΩ series resistor. Make sure these pins have no load that could pull them low at startup; otherwise, the receiver will enter its safeboot mode.

BlueSMiRF Header

The UART2 interface of the ZED-X20P can be accessed either through the BlueSMiRF header pins or the JST connector. The BlueSMiRF header can be used to connect the ZED-X20P GNSS module to external devices, such as a microcontroller or BlueSMiRF v2, Bluetooth® serial link.

BlueSMiRF header

The BlueSMiRF header pins on the ZED-X20P GNSS breakout board.

Supported Protocols

The UART interface supports the following protocols:

  • Input messages: NMEA and UBX
  • Output messages: NMEA (GGA, GLL, GSA, GSV, RMC, VTG, and TXT)

Configuration Settings

The UART interface can be configured with the CFG-UART2-* messages, but will initially have the following settings:

  • Baudrate: 9600 to 921600bps (Default: 38400bps)
  • Data Bits: 8
  • Parity: No
  • Stop Bits: 1
  • Flow Control: None

Bus Contention

To avoid bus contention issues between the BlueSMiRF header pins or the JST connector; make sure only one devices is connected to either of these connection options.

Pin Connections

When connecting the ZED-X20P GNSS breakout board to another device, users need to be aware of the pin connections and voltage ranges of the products. Below, is a table of the pin connections for the BlueSMiRF header pins on the ZED-X20P GNSS breakout board.

Pin Number 1
(Left Side) 		2 3 4 5 6
(Right)
Label NC TXD RXD 3V3 NC GND
Function UART - Transmit UART - Receive Output Voltage: 3.3V Ground

JST Connector

The UART2 interface of the ZED-X20P can be accessed either through the BlueSMiRF header pins or the JST connector. The JST connector can be used to connect the ZED-X20P GNSS module to external devices, such as the SiK Telemetry Radio V3 for RTK corrections.

JST Connector

The JST connector on the ZED-X20P GNSS breakout board.

Supported Protocols

The UART interface supports the following protocols:

  • Input messages: NMEA and UBX
  • Output messages: NMEA (GGA, GLL, GSA, GSV, RMC, VTG, and TXT)

Configuration Settings

The UART interface can be configured with the CFG-UART2-* messages, but will initially have the following settings:

  • Baudrate: 9600 to 921600bps (Default: 38400bps)
  • Data Bits: 8
  • Parity: No
  • Stop Bits: 1
  • Flow Control: None

Bus Contention

To avoid bus contention issues between the BlueSMiRF header pins or the JST connector; make sure only one devices is connected to either of these connection options.

Pin Connections

When connecting the ZED-X20P GNSS breakout board to another device, users need to be aware of the pin connections and voltage ranges of the products. Below, is a table of the pin connections for the JST connector on the ZED-X20P GNSS breakout board.

Pin Number 1
(Left Side) 		2 3 4
(Right)
Label 3V3 TXD RXD GND
Function Output Voltage: 3.3V UART - Transmit UART - Receive Ground

External Antenna

The ZED-X20P GNSS breakout board has two options for connecting an external GNSS antenna; the U.FL and SMA connectors. By default, the SMA connector is the primary interface. In order to utilize the U.FL connector, the RF jumper must be modified to redirect the signal path from the SMA connector. Then, an external antenna can be connected to the U.FL connector on the board with an U.FL to SMA adapter cable.

GNSS antenna inputs

The RF connections to attach an external GNSS antenna to the ZED-X20P GNSS breakout board.

RF jumper

The RF jumper that needs to be modified to utilize the U.FL connector.

Tip

For the best performance, we recommend users choose a compatible L1/L5 GNSS antenna and utilize a low-loss cable. Also, don't forget that GNSS signals are fairly weak and can't penetrate buildings or dense vegetation. The GNSS antenna should have an unobstructed view of the sky.

Status LEDs

Status LEDs

The status indicator LEDs on the ZED-X20P GNSS breakout board.

There are two status LEDs on the ZED-X20P GNSS 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 time pulse signal (see the PPS Output section)

  • RTK - RTK correction indicator (White)

    LED Status
    • On - Indicates that no carrier phase solution is available
    • Blinking - Indicates that a valid stream of correction messages is being received and utilized, but no RTK fixed mode has been achieved
    • Off - Indicates that RTK fixed mode has been achieved

  • FENCE - Geofence status indicator (Blue)

    LED Status
    • On - The GEOFENCE_STAT pin is always set to high level when the combined geofence state is unknown
    • Off - A low level can represent either an inside or outside state based upon the CFG-GEOFENCE-PINPOL configuration

Info

For low power applications, the LEDs can be disabled to conserve energy. See the Jumpers section.

Jumpers

Never modified a jumper before?

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

There are eight jumpers on the back of the board that can be used to easily modify the hardware connections on the board.

Jumpers

The jumpers on the bottom of the ZED-X20P GNSS breakout board.

LED Jumpers

Four of the jumpers control power to the status LEDs on the board.

Info

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.

  • 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, PPS LED that is provided by the PPS signal.
  • RTK - This jumper can be cut to remove power from the white, RTK correction LED.
  • FENCE - This jumper can be cut to remove power from the blue, Geofence status LED.
I2C
This jumper can be be modified to connect pull-up resistors to the SCL and SDA connections of the I2C interface.
SPI
This jumper is connected to the D_SEL pin and can be modified to enable the SPI interface on the RX, TX, SDA, and SCL pins.
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.
SHLD
This jumper can be cut to disconnect the shield of the USB-C connector from the board's ground plane.