MC68HC708MP16 Datasheet, PDF (156/398 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pulse Width Modulator for Motor Control (PWMMC)
DESIRED LOAD VOLTAGE
TOP PWM
BOTTOM PWM
LOAD VOLTAGE
Figure 9-25. Correction with Positive Current
DESIRED LOAD VOLTAGE
TOP PWM
BOTTOM PWM
LOAD VOLTAGE
Figure 9-26. Correction with Negative Current
9.6.4 Output Polarity
The output polarity of the PWMs is determined by two options: TOPNEG
and BOTNEG. The top polarity option, TOPNEG, controls the polarity of
PWMs 1, 3, and 5. The bottom polarity option, BOTNEG, controls the
polarity of PWMs 2, 4, and 6. Positive polarity means that when the PWM
is active, the PWM output is high. Conversely, negative polarity means
that when the PWM is active, PWM output is low. See Figure 9-27 and
Section 5. Configuration Register (CONFIG).
NOTE:
Both bits are found in the CONFIG register, which is a write-once
register. This reduces the chances of the software inadvertently
changing the polarity of the PWM signals and possibly damaging the
motor drive hardware.
Technical Data
156
MC68HC708MP16 — Rev. 3.1
Pulse Width Modulator for Motor Control (PWMMC) Freescale Semiconductor