SmartVFO – SDR VFO Control Knob, Buttons & CW Keyer

SmartVFO is a USB MIDI controller for SDR software, providing a rotary VFO knob, programmable buttons, and an integrated iambic CW keyer with local sidetone.

Built for the RP2040 (Raspberry Pi Pico) using the Arduino/earlephilhower core — produces a UF2 firmware file.

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🎛 Features

• Rotary Encoder as MIDI Knob — sends MIDI NoteOn/Off for left (CC 31) and right (CC 30) rotation with acceleration
• Iambic CW Keyer — Mode B iambic keyer with local sidetone buzzer
• WPM Adjustment — press encoder button (MIDI 32) to enter WPM adjust mode:
  • LED blinks red
  • "CQ CQ CQ" plays on local sidetone so you can hear the speed
  • Turn encoder to change WPM (5–50)
  • Press encoder again to confirm and exit
• LED Indicators:
  • 🟢 Green = normal operation
  • 🔴 Red = transmitting / WPM adjust mode
  • 🔵 Blue = startup
• 3 Buttons — encoder push (32), top (34), bottom (33) send MIDI notes
• Serial CW — type text over USB serial to transmit as CW
• Watchdog — 2-second hardware watchdog for reliability

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🔌 GPIO Pin Map

Function	GPIO
RGB LED Red	GP3
RGB LED Green	GP4
RGB LED Blue	GP5
Encoder A	GP17
Encoder B	GP16
Encoder Button	GP19
Button Top	GP18
Button Bottom	GP15
Dit Paddle	GP13
Dah Paddle	GP12
Buzzer	GP24

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🔧 Building

Prerequisites

• PlatformIO (CLI or VS Code extension)

Build & Flash

# Build
pio run

# Upload (with Pico in BOOTSEL mode)
pio run --target upload

# Generate UF2
# The .uf2 file will be in .pio/build/pico/

Manual Flash

1. Hold BOOTSEL on the Pico and connect USB
2. A drive named RPI-RP2 appears
3. Copy the .uf2 file to the drive
4. The Pico reboots with new firmware

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🎹 MIDI Map

Control	MIDI Note	Type
Encoder Left	31	NoteOn/Off
Encoder Right	30	NoteOn/Off
Encoder Button	32	NoteOn/Off
Button Bottom	33	NoteOn/Off
Button Top	34	NoteOn/Off
Dit Paddle*	35	NoteOn/Off
Dah Paddle*	36	NoteOn/Off
CW Key Down**	65	NoteOn/Off

* Non-CW mode only
** CW mode only

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⚙️ Configuration

Edit include/config.h before building:

• CW_MODE — true for iambic keyer, false for simple paddle/PTT
• DEFAULT_WPM — starting CW speed (default 15)
• SIDETONE_FREQ — buzzer frequency in Hz (default 880)
• MIN_WPM / MAX_WPM — WPM adjustment range

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📃 License

MIT License

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🧃 Credits

Developed by ON6URE – RF.Guru