PIC12F635/PIC16F636/639
2.2.2.5
PIR1 Register
The PIR1 register contains the interrupt flag bits, as
shown in Register 2-5.
Note:
Interrupt flag bits are set when an interrupt
condition occurs, regardless of the state of
its corresponding enable bit or the Global
Interrupt Enable bit, GIE of the INTCON
register. User software should ensure the
appropriate interrupt flag bits are clear
prior to enabling an interrupt.
REGISTER 2-5:
PIR1: PERIPHERAL INTERRUPT REQUEST REGISTER 1
R/W-0
EEIF
R/W-0
LVDIF
R/W-0
CRIF
R/W-0
C2IF(1)
R/W-0
C1IF
R/W-0
OSFIF
U-0
—
R/W-0
TMR1IF
bit 7
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
EEIF: EE Write Complete Interrupt Flag bit
1= The write operation completed (must be cleared in software)
0= The write operation has not completed or has not been started
LVDIF: Low-Voltage Detect Interrupt Flag bit
1= The supply voltage has crossed selected LVD voltage (must be cleared in software)
0= The supply voltage has not crossed selected LVD voltage
CRIF: Cryptographic Interrupt Flag bit
1= The Cryptographic module has completed an operation (must be cleared in software)
0= The Cryptographic module has not completed an operation or is Idle
C2IF: Comparator 2 Interrupt Flag bit(1)
1= Comparator output (C2OUT bit) has changed (must be cleared in software)
0= Comparator output (C2OUT bit) has not changed
C1IF: Comparator 1 Interrupt Flag bit
1= Comparator output (C1OUT bit) has changed (must be cleared in software)
0= Comparator output (C1OUT bit) has not changed
OSFIF: Oscillator Fail Interrupt Flag bit
1= System oscillator failed, clock input has changed INTOSC (must be cleared in software)
0= System clock operating
bit 1
bit 0
Unimplemented: Read as ‘0’
TMR1IF: Timer1 Overflow Interrupt Flag bit
1= Timer1 rolled over (must be cleared in software)
0= Timer1 has not rolled over
Note 1: PIC16F636/639 only.
DS41232D-page 30
© 2007 Microchip Technology Inc.
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