Program for converting ASCII code into Hex

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sangmeshwar

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Please give detail 8051 microcontroller program for converting ASCII code into HEX.

Thanks

Sangmeshwar
 

Here is the code (A is input and output):

Code: 
; ==============================================
; ASCII_Hex conversion routine...

ASC_Hex:	CJNE		A, #'0', Ch_1	; Test for ASCII numbers..
Ch_1:		JC		Ch_Bad		; Character is less than a '0'..
		CJNE		A, #'9'+1, Ch_2	; Test value range..
Ch_2:		JC		Ch_Val_109		; Character is between 0 and 9..

		CJNE		A, #'A', Ch_3		; Test for upper case hex letter..
Ch_3:		JC		Ch_Bad		; Character is less than 'A'..
		CJNE		A, #'F'+1, Ch_4	; Test value range..
Ch_4:		JC		Ch_Val_AF		; Character is between A and F..

Ch_Bad:	SETB		ErrFlag5		; Character is not a Hex number..
		LJMP		ASC_Hex_Exit

Ch_Val_AF:	CLR		C
		SUBB		A, #07h
Ch_Val_109:	CLR		C
		SUBB		A, #'0'
		CLR		ErrFlag5

ASC_Hex_Exit:RET

; ===================================================

Regards,
IanP
 

Ascii to hex - simple

Subtract hex 30 - check if result > 9 , if it is then subtract a further 7 - thats al that is required
 

Forgive me, I was feeling lazy and needed to do this function myself, so found these posts.


In the end I decided to write it myself as ascii - 0x30 does give you 0 to 9 but why - 7 ?

This "Simple" routine is also case freindly so 9E or 9e will both work, but there is no error checking.

Code: 
	; ***************************************************
	; * ASCII to HEX                                    *
	; * takes an ascii character and converts it to hex *
	; ***************************************************
	;
ASCIItoHEX:
	setb	ACC.5				; Strip case, lower case ascii 
	subb	a,#0x57				; value a - f will not carry
	jnc	ASCIIDone			; if not carry then we have converted the nibble
	add	a,#0x27				; Convert back to 0 - 9
ASCIIDone:
	ret
 

The - 7 is only required if the data contains letters of the alphabet. If you examine an ascii table you will see that between the numbers and letter are 7 symbols that need to be skipped. Assuming that this is hex data it will contain A - F and you will therefore need to - 7
 

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