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Hardware Assembly

USB Programming (UART1)

The USB connection can be utilized for serial communication and configuring the LG290P GNSS module. Users only need to connect their RTK Postcard to a computer, using a USB-C cable.

RTK Postcard USB connection

The RTK Postcard with USB-C cable being attached.

Default Baud Rate

The default baud rate of the UART ports on the LG290P is 460800bps.

GNSS Antenna

In order to receive GNSS signals, users will need to connect a compatible antenna. For the best performance, we recommend users choose an active, multi-band GNSS antenna and utilize a low-loss cable.

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.

Helical antenna

A compact, helical GNSS antenna attached to the SMA connector on the RTK Postcard.

Survey antenna

A GNSS survey antenna attached to the SMA connector on the RTK Postcard.

JST Connector (UART3)

The JST connector on the Quad-band GNSS RTK board, breaks out the UART3 port of the LG290P GNSS module. In most circumstances, users will utilize the JST connector to interface with one of our radios to transmit or receive RTK correction data.

Device connected to the JST connector

The Telemetry Radio v3 connected to the RTK Postcard.

When connecting the RTK Postcard to other products, users should be aware of the pin connections between the devices. The table below, details the pin connections of the locking JST connector on the RTK Postcard.

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

Default Baud Rate

The default baud rate of the UART ports on the LG290P is 460800bps.

Radio Transceivers

We have designed the locking JST connector to be plug-n-play with the following devices and cables. However, for the SiK Telemetry Radio v3, users should modify the VSEL jumper (1) on the back of the board to enable a 5V output on the VCC pin. Below, is a table summarizing the pin connections of the radios.

  1. While the SiK Telemetry Radio v3 may function with a 3.3V input, their specifications stipulate that a 5V power supply be provided.

Pin Number 1
(Left Side) 		2 3 4 5 6
(Right)
Label 5V RX - SiK
RXI - LoRaSerial 		TX - SiK
TXO - LoRaSerial 		CTS RTS GND
Function Voltage Input
- SiK: 5V
- LoRaSerial: 3.3 to 5V (1) 		UART - Receive UART - Transmit Flow Control
Clear-to-Send 		Flow Control
Ready-to-Send 		Ground

Radio Pin Connections

As documented in the LoRaSerial product manual, the pin connections between a host system (i.e. RTK Postcard) and the LoRaSerial radio is outlined in the image below.

UART w/ Flow Control
The pin connections between a radio and the RTK Postcard.

However, the flow control pins (CTS and RTS) are not available on the RTK Postcard. Therefore, when connecting either of the radios, the pin connections should follow the table below:

Board RX TX GND
Radio TX RX GND

Radio Transceivers and Cables

Default Baud Rate

The baud rate for these radios are configured by the SERIAL_SPEED parameter. The default configuration is SERIAL_SPEED: 57600bps.

Breakout Pins

The PTH pins on the Quad-band GNSS RTK board are broken out into 0.1"-spaced pins on the outer edges of the board.

New to soldering?

If you have never soldered before or need a quick refresher, check out our How to Solder: Through-Hole Soldering guide.

  • Headers

    When selecting headers, be sure you are aware of the functionality you require.

    Soldering headers
    Soldering headers to the RTK Postcard.

  • Hookup Wires

    For a more permanent connection, users can solder wires directly to the board.

    Soldering wires
    Soldering wires to the RTK Postcard.