Duty cycle resolution and printing to serial port about samd_slow_pwm

[khoih-prog]

set PWM duty cycle resolution to 8nsec which is a duty cycle resolution of 0.000008

There is no way this library, or even hardware-based PWM, can achieve that kind of absurd resolution of 8nsec.
You have to know that SAMD hardware timer clock is around 48MHz, and this slow PWM library can provide the accuracy around uSec or mSec range.

Also, when duty cycle is change the program prints to serial terminal. How can I turn the printing off?

Changing in the example to have

#define _PWM_LOGLEVEL_      0

SAMD_Slow_PWM/examples/SAMD21/ISR_Modify_PWM/ISR_Modify_PWM.ino

Line 26 in da5c3ce

#define _PWM_LOGLEVEL_ 4