sush
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external interrupt
hi
i am trying to make a system including frequency meter. for frequency
measurement method:- measuring time between two consequtive pulses. i'm
feeding the frequency at external interrupt pin. i'm facing a small
problem. when i start the system lcd displays the correct frequency
value. (i've added 5 seconds delay for refreshing the data) but second
time the frequency is refreshed the value comes wrong and after that
everytime absart values are displayed. i've tried everything. i've
tried re-intializing everything but nothing is helping out. here's the
code (the main part which measures freq. and displays it. Please help
me.
Kind regards.
hi
i am trying to make a system including frequency meter. for frequency
measurement method:- measuring time between two consequtive pulses. i'm
feeding the frequency at external interrupt pin. i'm facing a small
problem. when i start the system lcd displays the correct frequency
value. (i've added 5 seconds delay for refreshing the data) but second
time the frequency is refreshed the value comes wrong and after that
everytime absart values are displayed. i've tried everything. i've
tried re-intializing everything but nothing is helping out. here's the
code (the main part which measures freq. and displays it. Please help
me.
Kind regards.
Code:
LIST p=16F877A, W=2, X=ON, R=DEC ;tell assembler what chip we are using
include "P16F877A.inc" ;include the defaults for the chip
ERRORLEVEL 0, -302 ;suppress bank selection messages
__CONFIG 0x393A ;sets the configuration settings (oscillator type etc.)
cblock 0x20 ;start of general purpose registers
count
count1
counta
countb
COUNT_SEC
LoX
Bit_Cntr
Timer_H
Flags
Flags2
tmp1
tmp2
tmp3
NumL
NumH
AARGB0
AARGB1
AARGB2
AARGB3
BARGB0
BARGB1
LOOPCOUNT
REMB0
REMB1
TenK
Thou
Hund
Tens
Ones
templcd
templcd2
Acc1L ;16 bit maths register 1
Acc1H
Point ;position of decimal point
;FREQUENCY VARIABLES
FreqL
FreqH
TIMER1_LOW
TIMER1_HIGH
w_temp ; To save off current W register contents
status_temp
freq_over
endc
LCD_PORT Equ PORTD
LCD_TRIS Equ TRISD
LCD_RS Equ 0x05 ;LCD handshake lines
LCD_RW Equ 0x06
LCD_E Equ 0x07
ORG 0x0000
NOP
BCF PCLATH, 3
BCF PCLATH, 4
GOTO start
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>frequency call>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ORG 0x0004
MOVWF w_temp ; save off current W register contents
MOVF STATUS,w ; move status register into W register
MOVWF status_temp ; save off contents of STATUS register
BTFSC T1CON, TMR1ON
goto Stop_timer1
CLRF TMR1H
CLRF TMR1L
BSF T1CON, TMR1ON
GOTO END_ANS_INT
Stop_timer1
BCF T1CON, TMR1ON
MOVF TMR1H, W
MOVWF TIMER1_HIGH
MOVF TMR1L, W
MOVWF TIMER1_LOW
BSF freq_over, 0X00
;BCF INTCON, INTE
END_ANS_INT
MOVF status_temp,w ; retrieve copy of STATUS register
MOVWF STATUS ; restore pre-isr STATUS register contents
SWAPF w_temp,f
SWAPF w_temp,w ; restore pre-isr W register contents
BCF INTCON, INTF
retfie
;=====================================================================
start
errorlevel -302
bsf INTCON,INTE ; Enable external interrupt
bsf INTCON,GIE
Initialise clrf count
clrf PORTA
clrf PORTD
clrf PORTC
clrf Flags
clrf REMB0
clrf REMB1
movlw b'00110000'
movwf T1CON
SetPorts bsf STATUS, RP0 ;select bank 1
movlw 0x00 ;make all LCD pins outputs
movwf LCD_TRIS
movlw B'00000001' ;make all pins outputs
movwf TRISB
bsf OPTION_REG, NOT_RBPU
bcf STATUS, RP0 ;select bank 0
call LCD_Init ;setup LCD module
call LCD_CurOff ;turn cursor off
call Delay5
Main
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
;>>>>>>>>>>>>>>>>>>>>>>> READING VALUES FROM EXT. INT. FOR FREQUENCY >>>>>>>>>>>>>>>>>>>>>>
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
movlw b'00110000'
movwf T1CON
BCF freq_over, 0X00
bsf INTCON,INTE ; Enable external interrupt
CHECK_INT
BTFSS freq_over, 0X00
GOTO CHECK_INT
BCF INTCON,INTE
BCF freq_over, 0X00
CALL CALCULATE_FREQ
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> DISPLAY FREQ >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
movlw 0xC0 ;move to 1st row, first column
call LCD_Cmd
movf FreqH,w
movwf NumH
movf FreqL,w
movwf NumL
call LCD_Decimal ;and display on LCD (in decimal)
movlw ' '
call LCD_Char ;display a space
nop
nop
CALL Delay5sec
goto Main ;loop for ever
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> CALCULATE_FREQ >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
CALCULATE_FREQ
movlw 0x5F
movwf AARGB0
movlw 0x5E
movwf AARGB1
movlw 0x10
movwf AARGB2
movf TIMER1_HIGH,W
movwf BARGB0
movf TIMER1_LOW,W
movwf BARGB1
call FXD2416U ;DIVIDE 6250000/TIMER VALUE TO GET FREQUENCY WITH .1 RESOLUTION
movf AARGB1,w
movwf FreqH
movf AARGB2,w
movwf FreqL
RETLW 0X00
;>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
;LCD ROUTINES.........
;DIVIDE ROUTINES.......
end