MC68HC708MP16 Datasheet, PDF (171/398 Pages) Freescale Semiconductor, Inc – Microcontrollers

Pulse Width Modulator for Motor Control (PWMMC)
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 PWM Operation in Break Mode
If the microcontroller goes into break mode (or background mode), the
clocks to the PWM generator and output control blocks will freeze. This
allows the user to set a breakpoint on a development system and
examine the register contents and PWM outputs at that point. It also
allows the user to single-step through the code.
The clocks to the fault block will continue to run. Therefore, if a fault
occurs while the microcontroller is in break mode, the PWM outputs will
immediately be driven to their inactive state(s).
During break mode, the system integration module (SIM) controls
whether status bits in other modules can be cleared during the break
state. The BCFE bit in the SIM break flag control register (SBFCR)
enables software to clear status bits during the break state. (See 7.7.4
SIM Break Flag Control Register.)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect the PWMF and FFLAGx bits during the break state, make
sure BCFE is a logic 0. With BCFE at logic 0 (its default state), software
can read and write the status and control registers during the break state
without affecting the PWMF and FFLAGx bits.
MC68HC708MP16 — Rev. 3.1
Freescale Semiconductor Pulse Width Modulator for Motor Control (PWMMC)
Technical Data
171