-48-
Document Name
AI7688H
Reference Manual
Version
V 2.0
Date 2019/08/08
PWM
Use PWM module to generate a pulse width modulated signal pattern.
This is useful to control actuator peripherals such as servo motors. To use
PWM, initialize it on a certain pin such as GPIO. Note that only
GPIO18
,
GPIO19
,
GPIO20
,
GPIO21
supports PWM on AI7688H. To control the PWM
pattern, several parameters are required, including:
Period
This defines the carrier frequency of the modulation. It’s controlled by
period, period_ms and period_us APIs.
Duty Cycle or Pulse Width
These two parameters are related to each other and usually you only need
to set one of them. Duty cycle is controlled by write API with a value range
between 0.0 to 1.0, where 0.0 is 0% of duty cycle and 1.0 is 100% of duty
cycle.
Pulse width also defines the pattern in a different unit: the "uptime" of the
signal in time units.
This is defined by pulsewidth, pulsewidth_ms, and pulsewidth_us APIs.
The following example generates a 500Hz PWM signal with 25% duty cycle
on pin P26.
