blob: 27e607a923cf919624c6827a32432bef0b7d2130 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
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'
|
