Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
168 Pulse-Width Modulator for Motor Control (PWM MC) MOTOROLA
Pulse-Width Modulator for Motor Control 9.9 PWM Operation in Wait Mode
When the microcontroller is put in low-power wait mode via the WAIT
instruction, all clocks to the PWM module will continue to run. If an
interrupt is issued from the PWM module (via a reload or a fault), the
microcontroller will exit wait mode.
Clearing the PWMEN bit before entering wait mode will reduce power
consumption in wait mode because the counter, prescaler divider, and
LDFQ divider will no longer be clocked. In addition, power will be
reduced because the PWMs will no longer toggle.
9.10 Control Logic Block
This subsection provides a description of the control logic block.
9.10.1 PWM Counter Registers
The PWM counter registers (PCNTH and PCNTL) display the 12-bit
up/down or up-only counter. When the high byte of the counter is read,
the lower byte is latched. PCNTL will hold this latched value until it is
read. See Figure 9-32 and Figure 9-33.
Address: $0026
Bit 7654321Bit 0
Read: 0000Bit 11Bit 10Bit 9Bit 8
Write:
Reset:00000000
= Unimplemented
Figure 9-32. PWM Counter Register High (PCNTH)
Address: $0027
Bit 7654321Bit 0
Read: Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Write:
Reset:00000000
= Unimplemented
Figure 9-33. PWM Counter Register Low (PCNTL)