Enter a square clock of 12.5Khz, and change its duty cycle by pressing increase or decrease bottom. The change will be in steps of 10%. The increase and decrease inputs have an internal debouncer that could be disabled with the input disable_debouncer = 1.
Connect a signal clock (io_in), reset active high signal (io_in), a button to control the incremental input (io_in) and another button to control the decremental input(io_in), and finally forced to 0 the disable_debouncer input (io_in). The output signal will be in the pwm (io_out) port and the negate output in pwm_neg (io_out). The signal output will have a frecuency of clk/10 = 1.2Khz. When you press the incremental input bottom then the signal will increment by 10% Its duty cycle and when you press the decremental input bottom you will see that the output signal decrement by 10%.