
MC68336/376
TIME PROCESSOR UNIT
MOTOROLA
USER’S MANUAL
11-7
Refer to TPU programming note
Input Capture/Input Transition Counter (ITC) TPU
Function (TPUPN16/D) for more information.
11.4.3 Output Compare (OC)
The output compare function generates a rising edge, a falling edge, or a toggle of the
previous edge in one of three ways:
1. Immediately upon CPU32 initiation, thereby generating a pulse with a length
equal to a programmable delay time.
2. At a programmable delay time from a user-specified time.
3. As a continuous square wave. Upon receiving a link from a channel, OC refer-
ences, without CPU32 interaction, a specifiable period and calculates an offset:
where “RATIO” is a parameter supplied by the user.
This algorithm generates a 50% duty-cycle continuous square wave with each high/
low time equal to the calculated offset. Due to offset calculation, there is an initial link
time before continuous pulse generation begins.
Refer to TPU programming note
Output Compare (OC) TPU Function (TPUPN12/D)
for more information.
11.4.4 Pulse-Width Modulation (PWM)
The TPU can generate a pulse-width modulated waveform with any duty cycle from
zero to 100% (within the resolution and latency capability of the TPU). To define the
PWM, the CPU32 provides one parameter that indicates the period and another pa-
rameter that indicates the high time. Updates to one or both of these parameters can
direct the waveform change to take effect immediately, or coherently beginning at the
next low-to-high transition of the pin.
Refer to TPU programming note
Pulse-Width Modulation (PWM) TPU Function
(TPUPN17/D) for more information.
11.4.5 Synchronized Pulse-Width Modulation (SPWM)
The TPU generates a PWM waveform in which the CPU32 can change the period and/
or high time at any time. When synchronized to a time function on a second channel,
the synchronized PWM low-to-high transitions have a time relationship to transitions
on the second channel.
Refer to TPU programming note
Synchronized Pulse-Width Modulation (SPWM) TPU
Function (TPUPN19/D) for more information.
OFFSET
PERIOD RATIO
=
336376UMBook Page 7 Friday, November 15, 1996 2:09 PM