I recently completed development of a CHIRP driver for the KSUN M6 V2 UHF handheld transceiver. This project involved reverse-engineering the radio’s serial protocol, documenting the memory structure, and creating a fully-functional driver for the popular CHIRP radio programming software.

The complete driver, protocol documentation, and memory map specifications are available on GitHub: ksun-m6-v2-chirp-driver

Background

The KSUN M6 V2 is a compact UHF handheld radio operating in the 400-480 MHz range with 200 memory channels. While KSUN provides Windows-only programming software, there was no support for cross-platform tools like CHIRP. This meant Linux and macOS users were unable to program these radios.

The “V2” designation refers to a 2024+ hardware revision that uses a completely different serial protocol from the original M6. The new revision can be identified by the display text showing “CH001” instead of “CH-01” on the radio. The differences are significant:

Feature Original M6 M6 V2
Baud Rate 4,800 38,400
Block Size 16 bytes 128 bytes
Checksum Base 2 86
Channels 80 200
Start Address 0x0050 0x0300

This meant the existing M6 driver couldn’t be used and required creating an entirely new driver from scratch.

Reverse Engineering the Protocol

The reverse engineering process involved several approaches:

1. Serial Port Monitoring

I used serial port sniffing tools to capture communication between the manufacturer’s software and the radio. This revealed:

  • The radio uses a custom binary protocol (not AT commands)
  • Commands are 4 bytes with a checksum appended
  • Block reads return 132 bytes (3-byte echo + 128 data bytes + 1 checksum)
  • The radio requires multiple connection attempts (reliability issue)

2. Memory Dump Analysis

By comparing multiple memory dumps with known radio configurations, I was able to map out the memory structure:

0x0000-0x00FF: Configuration (256 bytes)
  - Radio settings (squelch, volume, backlight, etc.)
  - DES-encrypted password protection
  - Menu customization

0x0100-0x19FF: Channel Data (6400 bytes)
  - 200 channels × 32 bytes per channel
  - RX/TX frequencies (10 Hz precision)
  - CTCSS/DCS tones
  - Power, bandwidth, scan settings

3. Decompiling the Manufacturer’s Software

Using .NET decompilers, I analyzed the manufacturer’s C# application to understand:

  • Checksum algorithm (base 86 instead of the typical base 2)
  • Frequency encoding (stored in 10 Hz units as little-endian 32-bit integers)
  • Tone encoding (16-bit values with polarity bits)
  • The acceptable integer ranges for different features

Driver Features

The completed driver supports:

Memory Channels (200)

  • RX/TX frequencies with 10 Hz precision
  • Channel names (5 characters)
  • CTCSS/DCS tones (separate RX/TX)
  • Power level (High 2.0W / Low 0.5W)
  • Bandwidth (Wide 25kHz / Narrow 12.5kHz)
  • Scan add/skip
  • Scrambler, compander, busy lock
  • Encryption settings

Radio Settings

  • Startup text and channel
  • Language (Chinese Simplified/Traditional, English)
  • Beep, squelch, volume
  • Backlight brightness and timeout
  • VOX with threshold and delay
  • Battery save modes
  • Key lock with auto-lock
  • Time-out timer (TOT)
  • Frequency band limits
  • Channel limit (1-200)
  • And more…

Documentation

The project includes comprehensive technical documentation:

  • PROTOCOL_ANALYSIS.md - Complete serial protocol specification including command set, checksum algorithm, and communication sequences
  • MEMORY_MAP.md - Detailed memory structure, field encoding, and data format specifications

These documents serve both as developer references and educational resources for anyone interested in radio programming protocols.

Credits

This driver was developed using the CHIRP framework and builds upon the excellent work of the CHIRP development community. Special thanks to:

  • Dan Smith and the CHIRP Project team
  • Yuri D’Elia for the original KSUN M6 driver (which provided structural guidance)
  • The CHIRP developer documentation and coding standards

Conclusion

Developing this CHIRP driver was a rewarding exercise in reverse engineering, protocol analysis, and Python development. If you own a KSUN M6 V2 radio and want cross-platform programming support, give this driver a try!

The complete source code, documentation, and installation instructions are available at: https://github.com/b4ndit/ksun-m6-v2-chirp-driver

Questions, bug reports, and contributions are welcome!

License: The driver is released under GNU GPL v3 to maintain compatibility with the CHIRP project.