Keyer Schematic [best] — K3ng

Because the K3NG keyer is modular, you can add or remove features at any time. For example, if you initially built the keyer without a display, you can later add a 20×4 LCD and simply uncomment #define FEATURE_LCD_4BIT before re‑uploading the firmware. The same applies to a keyboard, memories, or a CW decoder.

A common point of confusion is the analog button matrix. In the generic K3NG schematic, a 10kΩ resistor is connected from +5V to the analog_buttons_pin . The "Command" button is then the first button connected to this pin. Following that, each memory button is separated by a 1kΩ resistor before connecting to the same analog line. When you press a button, it creates a specific voltage divider, creating a unique voltage that the Arduino's ADC can read. This design allows the keyer to distinguish between up to 12 different buttons using just one pin. k3ng keyer schematic