Septentrio GNSS Aiding IMX¶
The IMX can be configured for use with Septentrio GNSS receivers such as the Mosaic-G5. This can be done using either the EvalTool GNSS Setting tab or the IMX DID_FLASH_CONFIG.ioConfig and DID_FLASH_CONFIG.RTKCfgBits fields.
| GNSS Ports | Value |
|---|---|
| GNSS Source | serial 0, serial 1, or serial 2 |
| GNSS Type | Septentrio |
| GNSS1 Timepulse | Disable or IMX pin connected to Septentrio PPS |
| GNSS2 Timepulse | Disable |
| RTK Rover | Value |
|---|---|
| GNSS RTK Mode | Precision Position or Compass |
| RTK Base | Value |
|---|---|
| Serial Port 0 (Single GNSS only) | GNSS1 - RTCM3 |
| USB Port | GNSS1 - RTCM3 |
The following sections detail how to interface and configure the IMX for operation using a Septentrio receiver. See RTK precision positioning and RTK compassing for RTK operation principles.
Single-Receiver, Dual-Antenna Architecture¶
Unlike the ublox ZED or the GPX-1, which use two independent receiver modules for dual-antenna RTK compassing (one wired to GNSS1, a second to GNSS2), the Septentrio Mosaic-G5 is a single receiver with two antenna inputs (Main and Aux1). Only GNSS1 needs a Source and Type of Septentrio configured — GNSS2 stays disabled. Enabling RTK Compassing in RTKCfgBits tells the IMX to command the Mosaic-G5 into its own internal dual-antenna heading mode, rather than routing a second physical receiver.
How the IMX Talks to the Septentrio Receiver¶
The IMX communicates with the Septentrio receiver using its native SBF (Septentrio Binary Format) protocol rather than translating to/from RTCM or NMEA. Once a serial port's GNSS Type is set to Septentrio, the IMX automatically initializes the receiver:
- Raises the receiver's baud rate from its factory default of 115200 to the IMX's operating baud rate of 921600, and switches its own UART to match.
- Configures the receiver's antenna mode — multi-antenna heading mode if RTK Compassing is enabled, single-antenna otherwise.
- Enables SBF output on the port.
- Streams the position, velocity, satellite-visibility, and dual-antenna measurement messages the IMX needs, at a 500 ms (2 Hz) interval.
- Configures a 1 Hz PPS output from the receiver.
RTK correction data (RTCM3) received on any IMX serial port is forwarded byte-for-byte to the Septentrio receiver. The IMX withholds corrections until the initialization sequence above has completed.
Firmware Update¶
Septentrio GNSS firmware updates are performed through the IMX's own fwUpdate protocol — the same mechanism used for IMX application firmware updates — rather than the serial-bridge-plus-vendor-tool procedure used for ublox ZED receivers. Use cltool -ufpkg <package> or the EvalTool firmware update dialog; the IMX forwards the update to the Septentrio receiver internally.