Peter VK3TPM stripped down my 2k lines of code to 200, for a bare bones si5251 VFO. It thats all you want, then maybe try this. https://bitbucket.org/peter_marks/dc ...

A PLL VFO/controller for a multi-band SSB/CW transceiver, targeting Arduino Nano and si5351. The script is SP_VFO_Controller.ino. An initialiser script must be executed once to initialise EEPROM. This ...