mc68hc908ld64 Freescale Semiconductor, Inc, mc68hc908ld64 Datasheet - Page 171

• Manufacturer Part Number: mc68hc908ld64
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

12.1 Contents
12.2 Introduction
12.3 Functional Description
MC68HC908LD64
Freescale Semiconductor
Data Sheet — MC68HC908LD64
—
Rev. 3.0
12.2
12.3
12.4
12.4.1
12.4.2
Eight 8-bit PWM channels are available on the MC68HC908LD64.
Channels 0 to 7 are shared with port-B I/O pins under the control of the
PWM control register.
Each 8-Bit PWM channel is composed of an 8-bit register which contains
a 5-bit PWM in MSB portion and a 3-bit binary rate multiplier (BRM) in
LSB portion. There are eight PWM data registers, controlling each PWM
channel. The value programmed in the 5-bit PWM portion will determine
the pulse length of the output. The clock to the 5-bit PWM portion is the
system bus clock, the repetition rate of the output is hence 187.5kHz at
6MHz clock.
The 3-bit BRM will generate a number of narrow pulses which are
equally distributed among an 8-PWM-cycle frame. The number of pulses
generated is equal to the number programmed in the 3-bit BRM portion.
Example of the waveforms are shown in
Section 12. Pulse Width Modulator (PWM)
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
PWM Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
PWM Data Registers 0 to 7 (0PWM–7PWM). . . . . . . . . . . 173
PWM Control Register (PWMCR) . . . . . . . . . . . . . . . . . . . 174
Pulse Width Modulator (PWM)
Figure
12-4.
Data Sheet
171