PIC18F45J10 Datasheet, PDF (121/358 Pages) Microchip Technology – 28/40/44-Pin High-Performance RISC Microcontrollers with nanoWatt Technology

PIC18F45J10 FAMILY
EXAMPLE 11-1: IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE
RTCinit
RTCisr
MOVLW
MOVWF
CLRF
MOVLW
MOVWF
CLRF
CLRF
MOVLW
MOVWF
BSF
RETURN
BSF
BCF
INCF
MOVLW
CPFSGT
RETURN
CLRF
INCF
MOVLW
CPFSGT
RETURN
CLRF
INCF
MOVLW
CPFSGT
RETURN
CLRF
RETURN
80h
TMR1H
TMR1L
b’00001111’
T1CON
secs
mins
.12
hours
PIE1, TMR1IE
TMR1H, 7
PIR1, TMR1IF
secs, F
.59
secs
secs
mins, F
.59
mins
mins
hours, F
.23
hours
hours
; Preload TMR1 register pair
; for 1 second overflow
; Configure for external clock,
; Asynchronous operation, external oscillator
; Initialize timekeeping registers
;
; Enable Timer1 interrupt
; Preload for 1 sec overflow
; Clear interrupt flag
; Increment seconds
; 60 seconds elapsed?
; No, done
; Clear seconds
; Increment minutes
; 60 minutes elapsed?
; No, done
; clear minutes
; Increment hours
; 24 hours elapsed?
; No, done
; Reset hours
; Done
TABLE 11-2: REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reset
Values
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF
43
PIR1
PSPIF⁽¹⁾ ADIF
RCIF
TXIF SSP1IF CCP1IF TMR2IF TMR1IF
45
PIE1
PSPIE⁽¹⁾ ADIE
RCIE
TXIE SSP1IE CCP1IE TMR2IE TMR1IE
45
IPR1
PSPIP⁽¹⁾ ADIP
RCIP
TXIP SSP1IP CCP1IP TMR2IP TMR1IP
45
TMR1L Timer1 Register Low Byte
44
TMR1H Timer1 Register High Byte
44
T1CON
RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 44
Legend: Shaded cells are not used by the Timer1 module.
Note 1: These bits are not implemented on 28-pin devices and should be read as ‘0’.
© 2007 Microchip Technology Inc.
Preliminary
DS39682C-page 119