This has been very useful to me so I'll share it in case it is useful to others.
I have written an Arduino sketch that provides a simple command-line console (serial) to control most features of an Si5351/A.? This provides a very generic tool that can be used during the early phases of home-brew rig development when you just want to get the RF/IF chain up and running in a minimal way without fooling around with displays, encoders, Arduino coding, etc.? Just load up this sketch, connect the I2C pins to the Si5351/A, open he Serial Monitor (or other terminal program) and you're ready to start tuning.
There are some handy features that make it easy to deal with superhet math and filter pass-band tweaking. The details are here:?.
I'm doing a scratch-build of the BITX-40 with some modifications so I've been using this sketch a lot.? For my BITX I use CLK0 for the VFO, CLK2 for the BFO, and CLK1 as an RF signal injector/tester.? Here is a video of the receive side up and running:?
Happy New Year and 73s,
Bruce KC1FSZ?