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What's the difference between the ZED-F9P and the ZED-X20P?

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Contributors: [redacted]

Hardware Changes

With the exclusions of the added JST connector and adjusted location of the BlueSMiRF header; the overall board dimensions, edge connectors and screw-hole locations, and PTH pin layout are exactly the same.


Allband GNSS RTK Breakout - ZED-X20P (Qwiic)
GPS-RTK-SMA Breakout - ZED-F9P (Qwiic)
GPS-RTK2 Board - ZED-F9P (Qwiic)


Antenna Connection

Connector Options

With the ZED-F9P we released two different boards with either a U.FL connector or an SMA connector to attach a GNSS antenna. With the ZED-X20P, we have released a single board with both options with a jumper to select the connector to be used.

SMA: The location of the SMA connector remains the same.

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U.FL: The U.FL connector’s location is slightly different by a couple millimeters. There was a hole in the board to pass a U.FL cable through.

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Notes: We did our best to maintain an impedance match between the two different connections. Users may experience a small shift in the signal’s impedance after altering their board. However, in our experience, the GNSS receiver was still functional after modifying the jumper and we didn’t really notice a degradation in performance.

Length of SMA Connector

We recently changed suppliers for our SMA connector, so users will eventually see a slightly longer SMA connector on future boards.

Old version: 6.3mm
New version: 8mm

BlueSMiRF Header Location

On the ZED-F9P boards, the BlueSMiRF PTH pins were located at the edge of the board. For the ZED-X20P, we have added a locking JST connector, in its place, to allow users to easily attach an RF transceiver. Therefore, the BlueSMiRF header was relocated to the interior of the board.

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Notes: The pin layout of the BlueSMiRF header remains the same; connecting to the UART2 interface of the GNSS receiver. On the ZED-X20P, we added a VSEL jumper for users to switch between either a 5V or 3.3V input/output voltage for the BlueSMiRF header.

Pin Functionality

Most of the pin functionality remains the same, with the exception of a single pin. The safeboot pin on the ZED-Z20P board was relocated to a test point and replaced with the enable pin for the RT9080 LDO.



ZED-F9P: Safeboot Pin
ZED-X20P: RT9080 Enable Pin


Notes: The SPI interface is enabled with the DSEL jumper for the ZED-F9P; meanwhile, for the ZED-X20P, it is enabled with the SPI jumper. The operation of these jumpers remains the same; only the name changed on the silkscreen. Similarly, the EVENT and INT pins are both external interrupt pins; only the name changed on the silkscreen.

UART Interface

Baud rate:

  • ZED-F9P: 9600-921600 bps
  • ZED-X20P: 4800-8000000 bps
Notes: Default baud rate is 38400 bps. The ZED-F9P only supports the RTCM protocol up to v3.3

SPI Interface

Max transfer rate:

  • ZED-F9P: 125 kB/s
  • ZED-X20P: 880-950 kB/s

Max clock speed:

  • ZED-F9P: 5.5 MHz
  • ZED-X20P: 7.25-12.8 MHz
Notes: The transfer rate for the ZED-X20P is based on the load capacitance. SPI interface must be enabled by the jumper.

I2C Interface

The ZED-F9P only supported I2C fast-mode; while the ZED-X20P supports standard mode, fast mode, and fast mode plus.

Max bit rate:

  • ZED-F9P: 400 kbit/s
  • ZED-X20P: 1000 kbit/s

USB Interface

While both boards provide a USB-C connection to the GNSS receiver, on the ZED-X20P we would advise users not to rely on this interface in their designs.

Notes: For the ZED-X20P, we broke out this interface as part of a preliminary design recommendation. However, u-blox has recently removed this interface from their latest datasheet. Therefore, we would recommend that users not integrate this interface into their future designs. Especially when it doesn’t support firmware updates.
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