Amon Link

Amon Link

USB-powered RF bridge between Amon Ground Control (PC) and the Amon Lander drone, built around the WCH CH32V003F4P6 MCU with dual NRF24L01 + RFX2401C radios for robust range.

Part of the Amon Lander project:

• Amon Lander — overall vehicle, frame, test/control SW, and data
  https://github.com/TilenTinta/Amon_Lander
• Amon Board — flight controller hardware & firmware
  https://github.com/TilenTinta/Amon_Board
• Amon Ground Control — desktop GCS for telemetry & control
  https://github.com/TilenTinta/Amon_GroundControl_Software

Table of Contents

• Overview
• Features
  • Hardware
  • Software & Compatibility
  • Diagnostics & Controls
• Quick Start
• Flashing Firmware
• Debugging
  • LED Status Codes
  • Button Usage
• Repository Structure
• Roadmap
• Status & Disclaimer
• License
• Acknowledgments

Overview

Amon Link is a compact, low-power RF communication bridge that connects a PC-based Ground Control application to the Amon Lander over 2.4 GHz radios. It prioritizes reliability by pairing two NRF24L01 modules with the RFX2401C PA/LNA front-end for extended range and improved link quality. The board is powered from USB Type‑C and integrates a 3.3 V LDO.

Features

Hardware

• MCU: WCH CH32V003F4P6.
• Power: USB‑powered with onboard 3.3 V LDO.
• Connector: USB Type‑C.
• RF Link: Dual NRF24L01 radios with RFX2401C (PA+LNA) for long range and better SNR.
• Indicators/Controls: Status LED and button for reconnect/SW update.

Software & Compatibility

• Firmware: C, developed in MounRiver Studio IDE.
• USB–UART: CH340G bridge (install drivers if needed).
• Platforms: Works with Windows, Linux, and macOS Ground Control apps.
• Updates: Custom bootloader supports USB firmware updates.

Diagnostics & Controls

• Status LED for connection state.
• Button to trigger manual reconnect and entering bootloader mode.

Quick Start

1. Connect the Amon Link board to your PC using USB‑C.
2. Install drivers if required for CH340G.
3. Place antennas for the two NRF24L01 radios to ensure clear line‑of‑sight where possible.
4. Launch the Amon Ground Control application and select the appropriate COM port.

Flashing Firmware

• Open the project in MounRiver Studio IDE, compile, and upload to the CH32V003F4P6 MCU.

The board also includes a custom bootloader for USB firmware updates which is supported by the desktop software.

Bootloader

Firmware for device also includes bootloader option. To flash that:

• First flash bootloader (folder: Bootloader),
• after that you can flash main hex file over USB and desktop app (folder: Firmware)

If bootloader is not used you MUST modify the code in folder Firmware. In file Link.ld change code on the top of the file to:

/* Full flash 16KB */
__app_size = 16K;

MEMORY
{
  /* Application region - 16KB */  
	FLASH (rx) : ORIGIN = 0x00000000, LENGTH = __app_size 

  /* RAM - untouched 2KB */  
	RAM (xrw)  : ORIGIN = 0x20000000, LENGTH = 2K
}

SECTIONS
{
  .init :
  {
    ...

Once the bootloader is flashed, you can put your device in firmware update mode by holding the Reconnect button while plugging in the USB cable or by triggering it via software. When the blue and red LEDs are lights up, you're in firmware update mode!

The firmware can be updated using a graphical application. The application is built with a Python backend and an Electron front end. You can select and import either a hex or a binary file. Once imported, the CRC32 checksum is calculated for the file.

This checksum is used during device connection. When the device connects, a handshake process exchanges several pieces of data, one of which is the CRC32 value of the firmware currently installed on the device. If this CRC matches the one from the new file, you are notified before proceeding with the update. After a successful update, the new CRC32 value is written to the device for future reference.

Debugging

LED Status Codes

Button Usage

Press the button to trigger a manual reconnect attempt or befor powring up device to enter bootloader mode.

Range testing

The plan for this device is not to reach over 1 km of range, but only a few meters are enough for now. To test this, I did a simple test. I connected the device to my laptop and established a connection from the Ground control app to Amon Link and from that to Amon Lander. After receiving telemetry data, I started moving away from the drone. This test was done with line of sight between the drone and link device.

Because of field limitations, the test was not done until telemetry cut-off. The test will be repeated in the future to really get the limitation of radio range.

Status & Disclaimer

In active development. The hardware and firmware are usable, but changes are ongoing; expect rough edges as features evolve.