PWM generator

When to use it

Pulse-width modulation fakes an analog level from a digital pin: switch fast and vary the fraction of time the output is high. It's how you dim an LED, set a servo, or drive a motor from an FPGA, no DAC required.

How it works

A counter ramps 0 → 2^W-1 over and over, and the output is high while the counter is below duty. So duty sets the on-fraction: 0 is always off, max is always on. The demo uses duty = 5 of 16, about 31%.

Gotchas

• Update duty only at the wrap (when the counter is 0), changing it mid-pulse can produce a runt pulse. The verified lfpga_pwm handles this for you.
• Higher W gives finer steps but a lower PWM frequency for a given clock, trade resolution against flicker.