Microchip Technology DM183021 Data Sheet
2010 Microchip Technology Inc.
DS39616D-page 177
PIC18F2331/2431/4331/4431
FIGURE 18-4:
PWM TIME BASE BLOCK DIAGRAM
The PWM time base can be configured for four different
modes of operation:
• Free-Running mode
• Single-Shot mode
• Continuous Up/Down Count mode
• Continuous Up/Down Count mode with interrupts
modes of operation:
• Free-Running mode
• Single-Shot mode
• Continuous Up/Down Count mode
• Continuous Up/Down Count mode with interrupts
for double updates
These four modes are selected by the PTMOD<1:0>
bits in the PTCON0 register. The Free-Running mode
produces edge-aligned PWM generation. The
Continuous Up/Down Count modes produce
center-aligned PWM generation. The Single-Shot
mode allows the PWM module to support pulse control
of certain Electronically Commutated Motors (ECMs)
and produces edge-aligned operation.
bits in the PTCON0 register. The Free-Running mode
produces edge-aligned PWM generation. The
Continuous Up/Down Count modes produce
center-aligned PWM generation. The Single-Shot
mode allows the PWM module to support pulse control
of certain Electronically Commutated Motors (ECMs)
and produces edge-aligned operation.
PTMR Register
PTPER
Comparator
PTPER Buffer
Comparator
Zero Match
Period Match
PTMOD1
Up/Down
Timer Reset
F
OSC
/4
Clock
Control
Period Load
Duty Cycle Load
PTMOD1
Period Match
Zero Match
PTMR Clock
Interrupt
Control
PTMOD1
Period Match
Zero Match
PTMOD0
PTMOD0
PTEN
PTIF
PTDIR
PTMR Clock
Update Disable (UDIS)
Timer
Direction
Control
Postscaler
1:1-1:16
Prescaler
1:1, 1:4, 1:16, 1:64