Pulse-Width Modulator for Motor Control (PWMMC)
Control Logic Block
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Pulse-Width Modulator for Motor Control (PWMMC) 175
The IPOLx bits take effect at the beginning of the next load cycle,
regardless of the state of the load okay bit, LDOK.
IPOL2 — Top/Bottom Correction Bit for PWM Pair 2 (PWMs 3 and 4)
This buffered read/write bit selects which PWM value register is us ed
if top/bottom correction is to be achieved without current sensing.
1 = Use PWM value register 4.
0 = Use PWM value register 3.
NOTE: When reading this bit, the value read is the buffer val ue (not necessa rily
the value the output control block is currently using).
IPOL3 — Top/Bottom Correction Bit for PWM Pair 3 (PWMs 5 and 6)
This buffered read/write bit selects which PWM value register is us ed
if top/bottom correction is to be achieved without current sensing.
1 = Use PWM value register 6.
0 = Use PWM value register 5.
NOTE: When reading this bit, the value read is the buffer val ue (not necessa rily
the value the output control block is currently using).
PRSC1 and PRSC0 — PWM Prescaler Bits
These buffered read/write bits allow the PWM clock frequency to be
modified as shown in Table 9-9.
NOTE: When reading these bits, the value read is the buffer value (not
necessarily the value the PWM generator is currently using).
Table 9-9. PWM Prescaler
Prescaler Bits
PRSC1 and PRSC0 PWM Clock Frequency
00 fOP
01 fOP/2
10 fOP/4
11 fOP/8