MC908MR16CBE Datasheet, PDF (133/282 Pages) Freescale Semiconductor, Inc – The following revision history table summarizes changes contained in this document.

PWM VALUE REG. 1 = 1
PWM VALUE REG. 2 = 2
Output Control
IS1 POSITIVE
PWM = 1
PWM1
IS1 POSITIVE
PWM = 1
IS1 NEGATIVE
PWM = 2
IS1 NEGATIVE
PWM = 2
PWM2
Figure 12-20. Top/Bottom Correction for PWMs 1 and 2
12.5.4 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 12-21.
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.
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor
133