MC68HC05PV8 Datasheet, PDF (150/196 Pages) Freescale Semiconductor, Inc – Techinal Data - rev 1.9

Technical Data
Freescale Semiconductor, Inc.
11.4 Registers
Associated with the PWM system, there are a PWM data register, a
PWM period register and a PWM control register. These registers can
be written to and read at any time. Writing to the data or the period
register takes effect when the whole PWM system is started by switching
on the PWMON bit or when a conversion cycle is complete. After reset
the user should write to the prescaler bits prior to enabling the PWM
system. This prevents an erroneous duty cycle from being driven.
11.4.1 PWM Control Register
$002D Bit 7
6
5
4
3
2
1
Read:
PWMON POL
Write:
0
CYCLE PRA3 PRA2 PRA1
Reset: 0
0
0
0
0
0
0
Figure 11-4 PWM Control Register (PWMCR)
Bit 0
PRA0
0
PWMON – PWM Module On
1 = PWM module operating
0 = PWM module stopped
POL – PWM Polarity
When set, this bit makes the active PWM pulse high. When cleared,
the output is active low (e.g. $00 in the data register yields an all high
signal for POLA = 0). The programmed polarity bit is copied into a
shadow polarity bit when the PWM data register is written. At the end
of the current conversion, the shadow polarity bit takes effect.
1 = PWM polarity active high
0 = PWM polarity active low
CYCLE – PWM Cycle Completed
This bit indicates the completion (reload of PWM data and period) of
a PWM cycle. This flag is cleared by writing a 1 to the bit position.
1 = PWM registers were reloaded after last flag clear
0 = PWM registers were not reloaded after last flag clear
Technical Data
MC68HC(8)05PV8/A — Rev. 1.9
Pulse Width Modulator
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