MC9S12P128 Datasheet, PDF (327/564 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Chapter 10
Pulse-Width Modulator (PWM8B6CV1) Block Description
10.1 Introduction
The pulse width modulation (PWM) definition is based on the HC12 PWM definitions. The PWM8B6CV1
module contains the basic features from the HC11 with some of the enhancements incorporated on the
HC12, that is center aligned output mode and four available clock sources. The PWM8B6CV1 module has
six channels with independent control of left and center aligned outputs on each channel.
Each of the six PWM channels has a programmable period and duty cycle as well as a dedicated counter.
A flexible clock select scheme allows a total of four different clock sources to be used with the counters.
Each of the modulators can create independent continuous waveforms with software-selectable duty rates
from 0% to 100%. The PWM outputs can be programmed as left aligned outputs or center aligned outputs
10.1.1 Features
• Six independent PWM channels with programmable period and duty cycle
• Dedicated counter for each PWM channel
• Programmable PWM enable/disable for each channel
• Software selection of PWM duty pulse polarity for each channel
• Period and duty cycle are double buffered. Change takes effect when the end of the effective period
is reached (PWM counter reaches 0) or when the channel is disabled.
• Programmable center or left aligned outputs on individual channels
• Six 8-bit channel or three 16-bit channel PWM resolution
• Four clock sources (A, B, SA, and SB) provide for a wide range of frequencies.
• Programmable clock select logic
• Emergency shutdown
10.1.2 Modes of Operation
There is a software programmable option for low power consumption in wait mode that disables the input
clock to the prescaler.
In freeze mode there is a software programmable option to disable the input clock to the prescaler. This is
useful for emulation.
S12P-Family Reference Manual, Rev. 1.12
Freescale Semiconductor
327