The program is designed to control the frequency synthesizer according to the ICOM CI-V protocol.
To control the frequency of the synthesizer, you can use a program similar to OmniRig.
As the port, we indicate the serial port organized by Arduino itself.
As the type of transceiver, indicate Ike IC-706 (the brand of the transceiver can be changed inside the program).
The program implements only a few commands that control the frequency of the main local oscillator.
The necessary commands can be supplemented based on the directory. For instance - http:https://www.plicht.de/ekki/civ/civ-p0a.html
In the program, as an example, a synthesizer based on AD9850 is controlled.
The second version of the sketch implements support for the SI5351 synthesizer.
PS: Comments in the program, as well as articles in Russian. Sorry.
Вариант использования в качестве внешнего передатчика с SDR-приемником, пытался рассказать тут - http:https://www.cqham.ru/forum/showthread.php?31873-%D2%F0%E0%ED%F1%E8%E2%E5%F0-%E8%E7-RTL-SDR-%D0%E5%E0%EB%FC%ED%EE&p=1742043&viewfull=1#post1742043
Практическое использование, для управления SDR-приемников из программы HDSDR, посредством OmniRig, описал в этой заметке - http:https://blog.gengen.ru/?p=2209