I wanted to replace the drifty VFO in one of my rigs with a digital solution, but my hand-wired solution was messy, fiddly, and prone to ground loops and digital noise. So I designed a PCB and, well, I got carried away. The result is the UDVBM-1: a universal motherboard for an Arduino-compatible micro-controller (MCU) module and an Adafruit-compatible Si5351 PLL clock module.

The UDVBM-1 can be used in any rig for either the VFO or the BFO, or (usually) both. Additionally, the I2C, SPI, and 1-wire digital buses of the MCU are brought out to ports along the board edge to use for inputs (rotary encoders, buttons, and switches) and outputs (LCDs or other digital displays, panel idicators, buzzers, and cooling-fan control). To top it all off, the MCU’s analog-to-digital converter (ADC) inputs and pulse-width modulation (PWM) outputs are made available as well.

Currently, we have three versions of the fully-assembled UDVBM-1 available: one for the Arduino Nano, one for the Arduino Pro-Mini, and one for Seeed Studio’s family of Xiao MCU modules.

The UDVBM-1 offers these features:

• Board-edge connections (for use with or without headers) for I2C bus, SPI bus, 1-Wire bus, rotary encoder, ADC input, and PWM output.
• A manageable size, neither too big nor too small.
• Onboard linear regulator with back filter to keep digital noise out of the rig’s main supply.
• Available for the Arduino Nano and Pro-Mini or for the family of Seeed Studio Xiao microcontroller modules.
• Versions for the Arduino include a small breadboard area of isolated pads for additional user circuitry.

You have three buying options for the UDVBM-1: a bare PCB, a kit of PCB and discrete components (modules and SMA connectors not included), or a fully-assembled and tested unit (modules included; SMA connectors not included). Assembled and tested versions are produced when ordered and require up to 10 days for shipment.