Pic16f877a CCP1 - display values on a LCD screen

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Hi Guys

Hay I’m fairly new to all this programming but have been reading some threads on here and have read the MPlab tutorial so have a basic idea on how to start my programming project. So please be patient if I ask stupid questions .

So my set up I’m using
Chip: PIC16F877A
External Clock: using 8mhz crystal
Prototyping board scrounged from college
Software: MPLab IDE

(Please ask if you require further details)

Now I have a signal from an oscillator which varies roughly from 100hz to 1500hz. I wish to use the CCP on the Pic to sample the changing frequency of the oscillator. I then wish it to display values on a LCD screen. So far i have got the following code:

	list		p=16f877a	; list directive to define processor
	#include	<p16f877a.inc>	; processor specific variable definitions
	






;***** VARIABLE DEFINITIONS (examples)

; example of using Shared Uninitialized Data Section
INT_VAR		UDATA_SHR	0x71   
w_temp		RES     1		; variable used for context saving 
status_temp	RES     1		; variable used for context saving
pclath_temp	RES	1		; variable used for context saving

; example of using Uninitialized Data Section
TEMP_VAR	UDATA	0x20		; explicit address specified is not required
temp_count	RES	1		; temporary variable (example)


; example of using Overlayed Uninitialized Data Section
; in this example both variables are assigned the same GPR location by linker
G_DATA		UDATA_OVR		; explicit address can be specified
flag		RES	2		; temporary variable (shared locations - G_DATA)

G_DATA		UDATA_OVR   
count		RES	2		; temporary variable (shared locations - G_DATA)


;**********************************************************************
RESET_VECTOR	CODE	0x000		; processor reset vector
	nop				; nop required for icd
	movlw	high  start		; load upper byte of 'start' label
	movwf	PCLATH			; initialize PCLATH
	goto	start			; go to beginning of program


INT_VECTOR	CODE	0x004		; interrupt vector location
	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
	movf	PCLATH,w		; move pclath register into w register
	movwf	pclath_temp		; save off contents of PCLATH register

; isr code can go here or be located as a call subroutine elsewhere

	movf	pclath_temp,w		; retrieve copy of PCLATH register
	movwf	PCLATH			; restore pre-isr PCLATH register contents
	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
	retfie				; return from interrupt


MAIN	CODE
start

		CALL	PULSE			;Record timer reading when 1st pulse arrives
		MOVF	CCPR1L,0X0		;Save timer value in mem addresses 0X0 and 0X1 when 1st pulse arrives
		MOVF	CCPR1H,0X1 		
		CALL	PULSE			;Record timer reading when second pulse arrives 
		CLRF	CCP1CON			;Disbable more captures
		MOVF	CCPR1L,0X2  	;Save timer value in mem addresses 0x2 and 0x3 when 2nd pulse arrives
		MOVF	CCPR1H,0X3		
		CALL	RESULT			;Compute periode measured in clock cycles

PULSE	BCF		PIR1,CCP1IF		;Clear timer int flag
CHECK	BTFSS	PIR1,CCP1IF		;rising edge arrived? (bit test, skip if set)
		
RESULT	MOVF	0X0,W			;lst-pulse low byte reading to W
		SUBWF	0X2,F			;subtract W from 2nd-pulse low byte reading, save in mem address 0x2
		MOVF	0X1,W			;2nd-pulse high byte reading to W
		SUBWF	0x3,1			;Subtract W from 2nd-pulse high byte reading, save in mem address 0x3
		CALL	TABLE
;************************************************************************************

Now the questions so brace your self:

Is the following code above doing as i require (sampling each rise and calculating the difference between two and storing that in the W register)?

How do i go about creating a look up table that will take the value in the w register and compare it to values in the look up thus allowing me to display the value on a LCD screen?

Thanks

Mark