BL4S200 User’s Manual
33
PWM/PPM Outputs Setup
PWM and PPM outputs on the BL4S200 configurable I/O are configured using the
set-
PWM()
and
setPPM()
function calls. PWM and PPM outputs on the BL4S200 high-cur-
rent outputs are configured using the
setPWM_H()
and
setPPM_H()
function calls.
A PWM output is described as
noninverted
when it starts high, remains high for a duty
cycle that is a fraction of the period, then
goes low for the remainder of the period.
Similarly, an
inverted
PWM output starts
low, remains low for a duty cycle that is a
fraction of the period, then goes high for
the remainder of the period.
A PWM output is normally set up to start
when triggered by an event, and may be
set up so that the leading and trailing edges
of several PWM outputs are aligned as
long as the all the PWM outputs are on the
same block of a particular Rabbit RIO
chip.
A PPM ouput is similar to a PWM output,
except it is
shifted
by an
offset
relative to
the event that triggered the start of the
PPM output.
A PPM output is either inverted or nonin-
verted, based on whether it starts high or
low, and may be set up so that their lead-
ing and trailing edges of several PPM out-
puts are aligned as long as the all the PPM
outputs are on the same block of a particu-
lar Rabbit RIO chip
Period
Duty
Cycle
Inverted
Noninverted
PWM
OUTPUT
Period
Duty
Cycle
Shifted
PPM
OUTPUT
Offset
