mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 316

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

14.4.4 Pulse-Width Modulation (PWM)
14.4.5 Synchronized Pulse-Width Modulation (SPWM)
14.4.6 Period Measurement with Additional Transition Detect (PMA)
14.4.7 Period Measurement with Missing Transition Detect (PMM)
14-8
MOTOROLA
The TPU2 can generate a pulse-width modulated waveform with any duty cycle from
zero to 100% (within the resolution and latency capability of the TPU2). To define the
PWM, the CPU16 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.
The TPU2 generates a PWM waveform in which the CPU16 can change the period
and/or high time at any time. When synchronized to a time function on a second chan-
nel, the synchronized PWM low-to-high transitions have a time relationship to transi-
tions on the second channel.
Refer to TPU programming note Synchronized Pulse-Width Modulation (SPWM) TPU
Function (TPUPN19/D) for more information.
This function and the following function are used primarily in toothed-wheel speed-
sensing applications, such as monitoring rotational speed of an engine. The period
measurement with additional transition detect function allows for a special-purpose
23-bit period measurement. It can detect the occurrence of an additional transition
(caused by an extra tooth on the sensed wheel) indicated by a period measurement
that is less than a programmable ratio of the previous period measurement.
Once detected, this condition can be counted and compared to a programmable num-
ber of additional transitions detected before TCR2 is reset to $FFFF. Alternatively, a
byte at an address specified by a channel parameter can be read and used as a flag.
A non-zero value of the flag indicates that TCR2 is to be reset to $FFFF once the next
additional transition is detected.
Refer to TPU programming note Period Measurement, Additional Transition Detect
(PMA) TPU Function (TPUPN15A/D) for more information.
Period measurement with missing transition detect allows a special-purpose 23-bit pe-
riod measurement. It detects the occurrence of a missing transition (caused by a miss-
ing tooth on the sensed wheel), indicated by a period measurement that is greater than
a programmable ratio of the previous period measurement. Once detected, this con-
dition can be counted and compared to a programmable number of additional transi-
tions detected before TCR2 is reset to $FFFF. In addition, one byte at an address
specified by a channel parameter can be read and used as a flag. A non-zero value of
the flag indicates that TCR2 is to be reset to $FFFF once the next missing transition
is detected.
Freescale Semiconductor, Inc.
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MC68HC16Y3/916Y3
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