// Set CLK0 to output 14 MHz si5351.set_freq(1400000000ULL, SI5351_CLK0);

[xiaolaba]

example code of si5351_output.ino.

// Set CLK0 to output 14 MHz si5351.set_freq(1400000000ULL, SI5351_CLK0);
perhaps no complete understanding about the sample code or math,
14MHz is equally 14,000,000 or 14000000ULL in Hz,
what that means to be 1,400,000,000ULL, or typo alone ?

anyway, we got undesired output frequency with this testing code, far away from 14MHz or 10MHz.
please help.