Specifications

PWM Waveform Generation With Compare Units and PWM Circuits
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6.6.1 Generation of PWM Outputs With Event Manager
Each of the three compare units, together with GP timer 1 (in case of EVA) or
GP timer 3 (in case of EVB), the dead-band unit, and the output logic in the
event manager module, can be used to generate a pair of PWM outputs with
programmable dead-band and output polarity on two dedicated device pins.
There are six such dedicated PWM output pins associated with the three
compare units in each EV module. These six dedicated output pins can be
used to conveniently control 3-phase AC induction or brushless DC motors.
The flexibility of output behavior control by the compare action control register
(ACTRx) also makes it easy to control switched reluctance and synchronous
reluctance motors in a wide range of applications. The PWM circuits can also
be used to conveniently control other types of motors such as DC brush and
stepper motors in single or multi-axis control applications. Each GP timer
compare unit, if desired, can also generate a PWM output based on its own
timer.
Asymmetric and Symmetric PWM Generation
Both asymmetric and symmetric PWM waveforms can be generated by every
compare unit on the EV module. In addition, the three compare units together
can be used to generate 3-phase symmetric space vector PWM outputs. PWM
generation with GP timer compare units has been described in the GP timer
sections. Generation of PWM outputs with the compare units is discussed in
this section.
6.6.2 Register Setup for PWM Generation
All three kinds of PWM waveform generations with compare units and associ-
ated circuits require configuration of the same Event Manager registers. The
setup process for PWM generation includes the following steps:
- Setup and load ACTRx.
- Setup and load DBTCONx, if dead-band is to be used.
- Initialize CMPRx.
- Setup and load COMCONx.
- Setup and load T1CON (for EVA) or T3CON (for EVB) to start the opera-
tion.
- Rewrite CMPRx with newly determined values.