To convert Millimeters to Inches, Divide by 25.4 or multiply by .03937.
See http://www.piclist.com/cgi-bin/constdivmul.exe
For an eight bit value...
; ACC = ACC * 0.03937 ; Temp = TEMP ; ACC size = 8 bits ; Error = 0.5 % ; Bytes order = little endian ; Round = no ; ALGORITHM: ; Clear accumulator ; Add input / 32 to accumulator ; Add input / 128 to accumulator ; Add input / 4096 to accumulator ; Move accumulator to result ; ; Approximated constant: 0.0393066, Error: 0.160933 % ; Input: ACC0, 8 bits ; Output: ACC0, 4 bits ; Code size: 20 instructions cblock ACC0 TEMP0 endc ;copy accumulator to temporary movf ACC0, w movwf TEMP0 ;shift accumulator right 5 times swapf ACC0, w andlw 0x0F movwf ACC0 clrc rrf ACC0, f ;add temporary to accumulator movf TEMP0, w addwf ACC0, f ;shift accumulator right 2 times rrf ACC0, f clrc rrf ACC0, f ;add temporary to accumulator addwf ACC0, f ;shift accumulator right 5 times swapf ACC0, w andlw 0x0F movwf ACC0 skpnc bsf ACC0, 4 clrc rrf ACC0, f ; Generated by www.piclist.com/cgi-bin/constdivmul.exe (November 17, 2000 version) ; Tue Apr 03 14:37:32 2001 GMT