Intel 8XC196MC, 8XC196MD, 8XC196MH CHAPTER 9 WAVEFORM GENERA TOR

9-1
CHAPTER 9
WAVEFORM GENERA TOR
A waveform generator simplifies the task of generating synchronized, p ulse-width modulated
(PWM) outputs. This waveform generator is optimized for motion control applic ations 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 pa irs of compleme ntar y PWM outputs
that share a common carrier period, dead time, and operati ng 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 ge nerator and explains how to configure it. For detailed de-
scriptions of the signals discussed in this chapter, refer to Appendix B, “Signal Descripti ons.” For
additional information and application examples, consult AP-483, Application Examples Using
the 8XC196MC/MD Microcontroller (order number 272282).
9.1 WAVEFORM GENERATOR FUNCTIONAL OVERVIEW
The waveform generator (Figure 9-1 ) has three ma in parts: a timebase generator, phase driver
channels, and control circuitry. The timebase generator establishes the c arrier peri od, the phase
driver channels determine the duty cycle, and the control circuitry determi nes the operating mode
and controls interrupt generat ion. The waveform generat or’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 operat ing mode are the same for all three
phases; the duty cycle is independently programmable.