The above file in post #61, has floats for the CTCSS tone table and uses 26118 bytes or 85% of program storage space, 1072 bytes or 52% for variables.
The one below uses less as the CTCSS tone table is int, with the frequencies multiplies by 10 to include a decimal point, then converted to float and divided by 10 to restore the DP when used.
This saves a few bytes. Now 26046 bytes or 84% of program storage space, 990 bytes or 48% for variables.
Actually 4 less than displayed as the "OLED" was removed from the version name to make the display better.
No doubt even more memory could be saved with better optimizations.
For the Sept 11 2022 Ham Fest, I hope to have a few kits available for the basic VFO. There will be plenty of the bare boards for those who want source their own parts.
Here is the instructions, so far.
Reading the start of this thread, Note of caution using the Nano onboard 5 Volt regulator.
In my solar controllers designs that I have made in the past, I have used the Nano onboard 5 Volt regulator and found issues with both the quality of some Nanos that are clones and not originals (Most on Ebay's are clones).
The voltage drop across the regulator as you know is the source of the heat so if feeding the board with 12 Volts the voltage drop of 7 Volts times the current draw generates considerable heat, thus if drawing say 300 mA the device is dissipating 2.1 Watts that has no real heat sink, the Nano gets quite hot, especially if the heat is not taken away. As a design practice I have limited the running of external devices that draw small amounts of currents, if requiring more that 100 mA in total I have used external regulators of either switch mode or series type.