FlexRC-28 — Free open source RC-28 controller for SmartSDR (Windows)

stevew_m0rfc

Hi all,

I'd been using the RC-28 on the Mac with SmartSDR for Mac, which supports it natively, and thought it was a great bit of kit proper tuning dial, sensible buttons, feels like a real radio.

I was disappointed to find there was no equivalent support, so I decided to build it myself.

FlexRC-28 is a free Windows application that connects the Icom RC-28 USB encoder directly to SmartSDR.

What it does:

• Dial tuning with velocity-sensitive slow (10 Hz) and fast (100 Hz) step modes
• Automatic step snapping when switching between rates
• Snap to 1 kHz on panadapter click detects clicks vs mouse wheel automatically, so it only fires when you actually click to tune
• PTT momentary press-and-hold, or hold for 2.5 seconds to latch TX on; tap again to release. Great for ragchew where you don't want to hold the button the whole time
• F1/F2 buttons fully configurable by default: F1 cycles modes (LSB/USB/CW/AM), F2 cycles bands (160m through 6m) with automatic mode selection per band
• RIT control toggle, tune with the dial, display shows offset
• All four LEDs on the RC-28 working - Link goes solid green when connected, TX lights during transmit, F1/F2 reflect app state
• Connects to SmartSDR via the TCP API on port 4992 works alongside SmartSDR for Windows without interfering
• Radio auto-discovery finds your Flex on the local network automatically
• All button assignments configurable in the UI

How it works technically:

The RC-28's HID protocol isn't publicly documented, so the first step was reverse-engineering it from a USB capture using USBPcap and Wireshark. The byte map is now documented in the README for anyone who wants to build on it.

The app connects to SmartSDR via the standard TCP API (port 4992) using plain-text commands — slice tune, slice set mode=, xmit 1/0 etc. It runs alongside SmartSDR for Windows.

Download / source:

GitHub:

https://github.com/CerberusSolutions/FlexRC-28

(There's a Windows installer on the Releases page — no Node.js or build tools required, just download and run.)

Happy to answer questions. If you have a FLEX-8000 series or a different SmartSDR version and want to test it, I'd be interested to hear how it goes.

I cannot promise it is bug free and this was made for my personal use to fill-a-void. But I have been using it several days without any noticeable issues.

73,
Steve G0RFC