PIC18F2331 Datasheet, PDF (192/396 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High Performance PWM and A/D

PIC18F2331/2431/4331/4431
17.4.2 INTERRUPTS IN SINGLE-SHOT
MODE
When the PWM time base is in the Single-shot mode
(PTMOD<1:0> = 01), an interrupt event is generated
when a match with the PTPER register occurs. The
PWM timer register (PTMR) is reset to zero on the
following input clock edge, and the PTEN bit is cleared.
The postscaler selection bits have no effect in this
Timer mode.
17.4.3 INTERRUPTS IN CONTINUOUS
UP/DOWN COUNTING MODE
In the Up/Down Counting mode (PTMOD<1:0> = 10),
an interrupt event is generated each time the value of
the PTMR register becomes zero and the PWM time
base begins to count upwards. The postscaler
selection bits may be used in this mode of the timer to
reduce the frequency of the interrupt events.
Figure 17-7 shows the interrupts in continuous
Up/Down Counting mode.
FIGURE 17-6:
PWM TIME BASE INTERRUPT TIMING, SINGLE SHOT MODE
A: PRESCALER = 1:1
FOSC/4
PTMR
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
FFEh
2
FFFh
000h
000h
000h
1
1
1
PTMR_INT_REQ
PTIF bit
B: PRESCALER = 1:4
Q4 Q4
Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc Qc
PTMR
1
PTMR_INT_REQ
PTIF bit
FFEh
2
FFFh
1
000h
1
000h
000h
Note 1: Interrupt flag bit PTIF is sampled here (every Q1).
2: PWM Time Base Period register, PTPER, is loaded with the value FFFh for this example.
DS39616B-page 190
Preliminary
 2003 Microchip Technology Inc.