Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
170 Pulse-Width Modulator for Motor Control (PWM MC) MOTOROLA
Pulse-Width Modulator for Motor Control
9.10.3 PWMx Value Registers
Each of the six PWMs has a 16-bit PWM value register.
The 16-bit signed value stored in this register determines the duty cycle
of the PWM. The duty cycle is defined as: (PWM value/modulus) x 100.
Writing a number less than or equal to 0 causes the PWM to be off for
the entire PWM period. Writing a number greater than or equal to the
12-bit modulus causes the PWM to be on for the entire PWM period.
If the complementary mode is selected, the PWM pair s sh are PWM
value registers.
To avoid erroneous PWM pulses, this value is buffered and will not be
used by the PWM generator until the LDOK bit has been set and the next
PWM load cycle begins.
NOTE: When reading these registers, the value read is the buffer (not
necessarily the value the PWM generator is currently using).
Bit 7654321Bit 0
Read: Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8
Write:
Reset:00000000
Bold = Buffered
Figure 9-36. PWMx Value Registers High (PVALxH)
Bit 7654321Bit 0
Read: Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Write:
Reset:00000000
Bold = Buffered
Figure 9-37. PWMx Value Registers Low (PVALxL)