value multiplied 256

[ericgibbs]

i change the number from 32 to 40

Movlf .32,N ; Init Loop counter
Movlf .40,N ; Init Loop counter

; Bin To BCD conversion ( 32 bit word -> 8 digits )
; Bin in Result, Result+1, Result+2, Result+3
; BCD in BCD3, BCD2, BCD1, BCD0
Bin2BCD
clrc
Movlf .40,N ; Init Loop counter
clrf BCD3 ; Init result
clrf BCD2
clrf BCD1
clrf BCD0

when i measure 99mhz show on lcd 99.000.000
but when i measure 102mhz show on lcd [1] 02.000.000
why ;

hi,
By changing the 'bit counter' value to 40 from 32 you are trying process 5 bytes, but you only have 4 bytes to work with, so you are overflowing the conversion and so you are 'losing' the MSD ie: the "1".

 

[ericgibbs]

hi,
This is a fragment of the code I used to test the Bin2BCD/Disp, it works using the method stated in earlier posts.

;this is test data to check out the Bin2BCD and DispFreq Subr

;enter with a predivided value 100MHZ by 256 = 390.625
;the 0.625 is 'lost' so the final displayed value is 99,840

start:
	movlw 0x86; load the reg with 390.625 == 100,000/256
	movwf Result+3
	movlw 0x1
	movwf Result+2
	movlw 0x0
	movwf Result+1
	movlw 0x0
	movwf Result

;reposition the reg values == 390 * 256 
	movf Result+2,w
	movwf Result+1	;
	movf Result+3,w
	movwf Result+2
	movlw 0x0
	movwf Result+3

	call Bin2BCD
	call DispFreq; displayed value 99,840
	
lp1: goto lp1

 goto start

 

[savnik]

hi,
By changing the 'bit counter' value to 40 from 32 you are trying process 5 bytes, but you only have 4 bytes to work with, so you are overflowing the conversion and so you are 'losing' the MSD ie: the "1".

Finally i got the code to work right.
I change the 'bit counter' value to 40 from 32 and i add one byte BCD4.
Thank all for the help.