MC68HC908MR8 Datasheet, PDF (140/372 Pages) Motorola, Inc – Microcontrollers

Pulse-Width Modulator for Motor Control
9.12.5 PWM Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . .177
9.12.6 Dead-Time Write-Once Register . . . . . . . . . . . . . . . . . . .179
9.12.7 PWM Disable Mapping Write-Once Register . . . . . . . . .179
9.12.8 Fault Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . .180
9.12.9 Fault Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
9.12.10 Fault Acknowledge Register . . . . . . . . . . . . . . . . . . . . . .182
9.12.11 PWM Output Control Register. . . . . . . . . . . . . . . . . . . . .184
9.13 PWM Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185
9.2 Introduction
This section describes the pulse-width modulator for motor control
(PWMMC, version A). The MC68HC908MR8 PWM module can
generate three complementary PWM pairs or six independent PWM
signals. These PWM signals can be center-aligned or edge-aligned. A
block diagram of the PWM module is shown in Figure 9-1.
A 12-bit timer PWM counter is common to all six channels. PWM
resolution is one clock period for edge-aligned operation and two clock
periods for center-aligned operation. The clock period is dependent on
the internal operating frequency (f_OP) and a programmable prescaler.
The highest resolution for edge-aligned operation is 125 ns
(f_OP = 8 MHz). The highest resolution for center-aligned operation is
250 ns (f_OP = 8 MHz).
When generating complementary PWM signals, the module features
automatic dead-time insertion to the PWM output pairs.
A summary of the PWM registers is shown in Figure 9-2.
Technical Data
140
MC68HC908MR8 — Rev 4.1
Pulse-Width Modulator for Motor Control (PWMMC) Freescale Semiconductor