Here+ RTK Rover/Base Kit

This is a GNSS base/rover receiver set that was intended to be paired with UAVs using the Pixhawk flight controller. It is based on the NEO-M8P-0/2 which is capable of dual-constellation single band RTK. The base station is a GNSS only, and required a separate telemetry radio. The rover includes the GNSS as well as I2C modules for IMU, mag, and barometric pressure.

• https://docs.px4.io/v1.11/en/gps_compass/rtk_gps_hex_hereplus
• https://sccdn.sechitech.com/muginuav/uploads/2025/06/Herev2-User-Manual-1.pdf

U-Blox NEO-M8P-2 with a USB port and exposed pins for UART1 Rx/Tx/GND. SMA for antenna. The -2 variant of the M8P can be used as an RTK base or rover, sending or receiving RTCM corrections.

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The rover hardware includes a GNSS + antenna and six I2C devices. It has an eight pin JST-GH connector which is externally accessible by way of a cable passthrough in the case which carries the UART and I2C to the flight controller. It also has a four pin connector (also JST-GH) for USB, though only data is carried on this connector, power must be applied via the larger connector.

The Here+ v1 rover differs significantly from the 2/3/4 in that the sensors are connected to the I2C bus directly, and the module does not support the CAN protocol. In the 2/3/4, the sensors are connected to an STM32 which can either emulate I2C devices, or provide the data on a CAN bus. For the purposes of tinkering/hacking, having the hardware exposed directly via their own I2C interfaces has some advantages.

The rover's GNSS is a U-Blox NEO-M8P-0. It is accessible via UART1 on the eight pin connector, and USB on the four pin connector (it uses the same as the base unit.) Note: the USB connector does not supply power to the rover or the GNSS module, voltage must be separately applied to pin 1 of the eight pin connector.

The GNSS antenna is a Taoglas CGGBP.25.4.A.02 1“ ceramic patch.

Solid purple, lowest brightness (still quite bright!)

TCA62724_Purple.ino

#include <Wire.h>
 
#define TCA62724_ADDR   0x55
#define SDA_PIN         10
#define SCL_PIN         9
 
void setup() {
    Wire.begin(SDA_PIN, SCL_PIN);
    delay(10);
 
    // Enable the LED driver
    Wire.beginTransmission(TCA62724_ADDR);
    Wire.write(0x84);  // Enable register
    Wire.write(0x03);  // Turn on
    Wire.endTransmission();
 
    // Set Purple: Red=1, Green=0, Blue=1 (lowest brightness)
    Wire.beginTransmission(TCA62724_ADDR);
    Wire.write(0x81);  // Blue register
    Wire.write(1);     // Blue = 1
    Wire.write(0x82);  // Green register
    Wire.write(0);     // Green = 0
    Wire.write(0x83);  // Red register
    Wire.write(1);     // Red = 1
    Wire.endTransmission();
}
 
void loop() {
    // Nothing - LED stays purple
}