CHAPTER 9

WAVEFORM GENERATOR

A waveform generator simplifies the task of generating synchronized, pulse-width modulated (PWM) outputs. This waveform generator is optimized for motion control applications such as driving 3-phase AC induction motors, 3-phase DC brushless motors, or 4-phase stepping motors. The waveform generator can produce three independent pairs of complementary PWM outputs that share a common carrier period, dead time, and operating mode. Once it is initialized, the waveform generator operates without CPU intervention unless you need to change a duty cycle.

This chapter describes the waveform generator and explains how to configure it. For detailed de- scriptions of the signals discussed in this chapter, refer to Appendix B, “Signal Descriptions.” For additional information and application examples, consult AP-483, Application Examples Using the 8XC196MC/MD Microcontroller (order number 272282).

9.1WAVEFORM GENERATOR FUNCTIONAL OVERVIEW

The waveform generator (Figure 9-1) has three main parts: a timebase generator, phase driver channels, and control circuitry. The timebase generator establishes the carrier period, the phase driver channels determine the duty cycle, and the control circuitry determines the operating mode and controls interrupt generation. The waveform generator’s maximum frequency is 15.625 kHz for center-aligned modes and 31.250 kHz for edge-aligned modes.

There are three independent phases, each of which has two programmable, complementary out- puts. A programmable “dead-time” generator prevents the complementary outputs from being ac- tive at the same time. The carrier period, dead time, and operating mode are the same for all three phases; the duty cycle is independently programmable.

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Intel 8XC196MC, 8XC196MD, 8XC196MH manual Chapter Waveform Generator, Waveform Generator Functional Overview