You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
54 lines
1.9 KiB
54 lines
1.9 KiB
list p=16f877
|
|
#include <p16f877.inc>
|
|
|
|
__CONFIG _CP_ALL & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _RC_OSC & _WRT_ENABLE_ON & _LVP_ON & _CPD_OFF
|
|
|
|
;**********************************************************************
|
|
BANK0 = 0x0
|
|
BANK1 = 0x80
|
|
BANK2 = 0x100
|
|
BANK3 = 0x180
|
|
|
|
;**********************************************************************
|
|
w_saved EQU 0x70 ; variable used for context saving
|
|
status_saved EQU 0x71 ; variable used for context saving
|
|
index EQU 0x20
|
|
|
|
;**********************************************************************
|
|
ORG 0x000 ; processor reset vector
|
|
movlw high start ; load upper byte of 'start' label
|
|
movwf PCLATH ; initialize PCLATH
|
|
goto start ; go to beginning of program
|
|
|
|
;**********************************************************************
|
|
ORG 0x004 ; interrupt vector location
|
|
movwf w_saved
|
|
movfw STATUS
|
|
movwf status_saved
|
|
|
|
bcf INTCON,2 ; reset TMR0 interrupt flag
|
|
|
|
movfw status_saved
|
|
movwf STATUS
|
|
swapf w_saved,f
|
|
swapf w_saved,w
|
|
retfie ; return from interrupt
|
|
|
|
;**********************************************************************
|
|
start
|
|
; initialize microchip
|
|
clrf TMR0 ^ BANK0
|
|
clrf INTCON ^ BANK0
|
|
banksel TRISA ; bank 1
|
|
movlw B'11010100' ; set prescaler at 32 (32768 Hz / 4 / 256 / 32 = 1 Hz)
|
|
movwf OPTION_REG ^ BANK1 ; and start TMR0 (internal source clock)
|
|
movlw B'00000110' ; set PORTA and PORTE to be all digital
|
|
movwf ADCON1 ^ BANK1
|
|
banksel INTCON ; back to bank 0
|
|
bsf INTCON,T0IE ; enable TMR0 interrupt
|
|
bsf INTCON,GIE ; enable all interrupts
|
|
|
|
; loop forever
|
|
goto $
|
|
END ; directive 'end of program'
|