
PIC17C4X
DS30412B-page 24
1996 Microchip Technology Inc.
5.3
Peripheral Interrupt Request Register
(PIR)
This register contains the individual flag bits for the
peripheral interrupts.
Note:
These bits will be set by the specified con-
dition, even if the corresponding interrupt
enable bit is cleared (interrupt disabled), or
the GLINTD bit is set (all interrupts dis-
abled). Before enabling an interrupt, the
user may wish to clear the interrupt flag to
ensure that the program does not immedi-
ately branch to the peripheral interrupt ser-
vice routine.
FIGURE 5-4: PIR REGISTER (ADDRESS: 16h, BANK 1)
R/W - 0
RBIF
bit7
R/W - 0
TMR3IF TMR2IF TMR1IF
R/W - 0
R/W - 0
R/W - 0
CA2IF
R/W - 0
CA1IF
R - 1
TXIF
R - 0
RCIF
bit0
R = Readable bit
W = Writable bit
-n = Value at POR reset
bit 7:
RBIF
1 =One of the PORTB inputs changed (Software must end the mismatch condition)
0 =None of the PORTB inputs have changed
TMR3IF
: Timer3 Interrupt Flag bit
If Capture1 is enabled (CA1/PR3 = 1)
1 =Timer3 overflowed
0 =Timer3 did not overflow
If Capture1 is disabled (CA1/PR3 = 0)
1 =Timer3 value has rolled over to 0000h from equalling the period register (PR3H:PR3L) value
0 =Timer3 value has not rolled over to 0000h from equalling the period register (PR3H:PR3L) value
TMR2IF
: Timer2 Interrupt Flag bit
1 =Timer2 value has rolled over to 0000h from equalling the period register (PR2) value
0 =Timer2 value has not rolled over to 0000h from equalling the period register (PR2) value
TMR1IF
: Timer1 Interrupt Flag bit
If Timer1 is in 8-bit mode (T16 = 0)
1 =Timer1 value has rolled over to 0000h from equalling the period register (PR) value
0 =Timer1 value has not rolled over to 0000h from equalling the period register (PR2) value
If Timer1 is in 16-bit mode (T16 = 1)
1 =TMR1:TMR2 value has rolled over to 0000h from equalling the period register (PR1:PR2) value
0 =TMR1:TMR2 value has not rolled over to 0000h from equalling the period register (PR1:PR2) value
CA2IF
: Capture2 Interrupt Flag bit
1 =Capture event occurred on RB1/CAP2 pin
0 =Capture event did not occur on RB1/CAP2 pin
CA1IF
: Capture1 Interrupt Flag bit
1 =Capture event occurred on RB0/CAP1 pin
0 =Capture event did not occur on RB0/CAP1 pin
TXIF
: USART Transmit Interrupt Flag bit
1 =Transmit buffer is empty
0 =Transmit buffer is full
RCIF
: USART Receive Interrupt Flag bit
1 =Receive buffer is full
0 =Receive buffer is empty
: PORTB Interrupt on Change Flag bit
bit 6:
bit 5:
bit 4:
bit 3:
bit 2:
bit 1:
bit 0: