This post concerns the Open ARDF Equipment Project, which is utilizing the Receiver Development Platform, both of which are being developed together.
The first Rev X1 Control Head and Digital Interface boards are now working together. The Control Head is able to set the frequency of the Si5351 IC on the Digital Interface as shown on the display. Not all of the components have been tested on the Digital Interface yet, and the separate processors are not yet communicating with one another. But at least they are not interfering with one another!
The earphone plugged into the Digital Interface enables the power on both boards. The red LED indicates that the LiPo battery (upper right) is being charged by the USB cable (center right). The twisted pair of wire-wrap wires running between the boards (upper left) is connecting the I2C bus between the two boards.