Microchip Technology DM164130-10 User Manual
PSMC Designer User’s Guide
DS40001671B-page 22
2012-2013 Microchip Technology Inc.
FIGURE 2-8:
MODULATION CONTROL
2.18.1
Modulation Source Selection
The modulation source is selected from one of the external asynchronous PSMC inputs
or peripheral outputs internal to the device. Modulation sources are mutually exclusive.
The selection is made by choosing the desired source from those available in the
Modulation Source combination box. Note that when modulation is enabled and the
modulation source is low, then the Timer is held in Reset. This ensures that the first
PWM pulse enabled by the modulation going high is a complete PWM period.
Synchronization with the period event ensures that the last PWM pulse is also a
complete period. It should be apparent that modulation should only be used when the
PWM Q signal is completely synchronous (no asynchronous inputs to the period, rising,
or falling events) to avoid an incomplete cycle of the first PWM period after modulation
starts.
or peripheral outputs internal to the device. Modulation sources are mutually exclusive.
The selection is made by choosing the desired source from those available in the
Modulation Source combination box. Note that when modulation is enabled and the
modulation source is low, then the Timer is held in Reset. This ensures that the first
PWM pulse enabled by the modulation going high is a complete PWM period.
Synchronization with the period event ensures that the last PWM pulse is also a
complete period. It should be apparent that modulation should only be used when the
PWM Q signal is completely synchronous (no asynchronous inputs to the period, rising,
or falling events) to avoid an incomplete cycle of the first PWM period after modulation
starts.
2.18.2
Modulation Enable
Modulation is enabled by clicking the enable switch to the On position. When enabled,
the modulation signal gates the Q output from the PWM SR latch to the PWM mode
input. Note that the PWM coming into the modulation function is labeled Q and going
out it is labeled MQ. Modes that use the PWM signal take their input from the
modulation function MQ output.
When the modulation enable switch is in the Off position, the MQ gate is always
enabled, thereby passing the unmodulated Q out to the mode inputs.
the modulation signal gates the Q output from the PWM SR latch to the PWM mode
input. Note that the PWM coming into the modulation function is labeled Q and going
out it is labeled MQ. Modes that use the PWM signal take their input from the
modulation function MQ output.
When the modulation enable switch is in the Off position, the MQ gate is always
enabled, thereby passing the unmodulated Q out to the mode inputs.
2.19 PSMC MODES
The mode function is where the simple PWM signal derived from the rising and falling
events becomes something more. There are five PWM modes, one High Resolution
Frequency mode, and one Six-Step mode that simplifies steering pairs of outputs to the
six PWM channels.
All modes, except the Six-Step mode, have a corresponding complementary output
mode making a total of thirteen modes (2 x 6 + 1 = 13). The complementary modes
include two dead-band controls: one triggered by the rising edge of the PWM signal
and one triggered by the falling edge.
Modes are selected by clicking on the corresponding tab in the mode selection GUI.
The tabs are labeled with the acronym of the mode control contained therein.
There are up to six PWM output channels. Not all modes use all six channels. Unused
channels are indicated by an output line that begins with an X. The sections that follow
detail each of the thirteen modes.
events becomes something more. There are five PWM modes, one High Resolution
Frequency mode, and one Six-Step mode that simplifies steering pairs of outputs to the
six PWM channels.
All modes, except the Six-Step mode, have a corresponding complementary output
mode making a total of thirteen modes (2 x 6 + 1 = 13). The complementary modes
include two dead-band controls: one triggered by the rising edge of the PWM signal
and one triggered by the falling edge.
Modes are selected by clicking on the corresponding tab in the mode selection GUI.
The tabs are labeled with the acronym of the mode control contained therein.
There are up to six PWM output channels. Not all modes use all six channels. Unused
channels are indicated by an output line that begins with an X. The sections that follow
detail each of the thirteen modes.