PIC17C42-25/P View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC17C42-25/P

High-Performance 8-Bit CMOS EPROM/ROM Microcontroller

Microchip Technology 

PIC17C4X

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 R/W - 0 R/W - 0 R/W - 0 R/W - 0 R/W - 0 R - 1 R - 0

RBIF

bit7

TMR3IF TMR2IF TMR1IF CA2IF

CA1IF

TXIF

RCIF

bit0

R = Readable bit

W = Writable bit

-n = Value at POR reset

bit 7: RBIF: PORTB Interrupt on Change Flag bit

1 = One of the PORTB inputs changed (Software must end the mismatch condition)

0 = None of the PORTB inputs have changed

bit 6:

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

bit 5:

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

bit 4:

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

bit 3:

CA2IF: Capture2 Interrupt Flag bit

1 = Capture event occurred on RB1/CAP2 pin

0 = Capture event did not occur on RB1/CAP2 pin

bit 2:

CA1IF: Capture1 Interrupt Flag bit

1 = Capture event occurred on RB0/CAP1 pin

0 = Capture event did not occur on RB0/CAP1 pin

bit 1:

TXIF: USART Transmit Interrupt Flag bit

1 = Transmit buffer is empty

0 = Transmit buffer is full

bit 0:

RCIF: USART Receive Interrupt Flag bit

1 = Receive buffer is full

0 = Receive buffer is empty

DS30412C-page 24

© 1996 Microchip Technology Inc.

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