Chapter 12

Pulse-Width Modulator for Motor Control (PWMMC)

12.1 Introduction

This section describes the pulse-width modulator for motor control (PWMMC, version A). The 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 12-2.

A12-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 (fOP) and a programmable prescaler. The highest resolution for edge-aligned operation is 125 ns (fOP = 8 MHz). The highest resolution for center-aligned operation is 250 ns (fOP = 8 MHz).

When generating complementary PWM signals, the module features automatic dead-time insertion to the PWM output pairs and transparent toggling of PWM data based upon sensed motor phase current polarity.

A summary of the PWM registers is shown in Figure 12-3.

12.2 Features

Features of the PWMMC include:

•Three complementary PWM pairs or six independent PWM signals

•Edge-aligned PWM signals or center-aligned PWM signals

•PWM signal polarity control

•20-mA current sink capability on PWM pins

•Manual PWM output control through software

•Programmable fault protection

•Complementary mode featuring:

–Dead-time insertion

–Separate top/bottom pulse width correction via current sensing or programmable software bits

MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1

Freescale Semiconductor

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Freescale Semiconductor MC68HC908MR16, MC68HC908MR32 manual Chapter Pulse-Width Modulator for Motor Control Pwmmc, Features
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MC68HC908MR16, MC68HC908MR32 specifications

Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are part of the popular HC08 family, designed primarily for embedded applications. These microcontrollers are particularly favored in automotive, industrial, and consumer product sectors due to their reliability and versatility.

One of the standout features of the MC68HC908MR series is its CMOS technology, which enhances performance while minimizing power consumption. This makes these microcontrollers suitable for battery-operated devices. They operate at a maximum clock frequency of 2 MHz and offer a 16-bit architecture, providing a solid balance between processing power and efficiency.

The MC68HC908MR32 variant is equipped with 32KB of flash memory, which allows for the storage of complex programs and extensive data handling. In contrast, the MC68HC908MR16 features 16KB of flash memory, making it ideal for simpler applications. Both microcontrollers also come with 1KB of RAM, enabling efficient data processing and real-time operations.

Another significant characteristic of these microcontrollers is their integrated peripherals. They come with multiple input/output (I/O) pins, which allow for connectivity with various sensors and actuators. The built-in timer systems offer precise timing control for automotive and industrial applications, while the Analog-to-Digital Converter (ADC) provides essential conversion capabilities for various analog signals.

For communication purposes, the MC68HC908MR series includes a serial communication interface, enabling easy integration with other devices and systems. This versatility facilitates the development of complex systems that require interaction with external components.

Security is another crucial aspect of these microcontrollers. They have built-in fail-safe mechanisms to ensure reliable operation under various conditions, making them suitable for critical systems. Additionally, their robust architecture helps to safeguard against potential disruptions or attacks.

In summary, Freescale Semiconductor's MC68HC908MR32 and MC68HC908MR16 microcontrollers are key players in the embedded systems landscape. Their blend of power efficiency, integrated features, and scalability ensures they remain relevant for a wide array of applications, making them a favored choice among engineers and developers looking for dependable solutions in a competitive market.
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