+ 5V
   |
   |
   |          
   / R1      100k
   /<--+ LDR 
   /   |     
   /   |     
   +---+-------> I/O PORT 
   |
   =   C1: 100 nF
   |
   |
   + GND	 

; ***************************************
; * Get the pot value
; ***************************************

LDR       BIT   P3.3
LICHT     DATA  5Eh

GETLIGHT: CLR   LDR       ; Discharge capacitor
          MOV   A,#100    ; Wait until empty
WACHT:    DJNZ  ACC,WACHT ; A is zero
	  SETB  LDR	  ; C starts loading 
  	  
LDR10:	  JB    LDR,LDR20 ; It is high 
 	  INC   A         ; Count the time it takes  
	  JNZ   LDR10     ; to get high, Overflow   
	  DEC   A	  ; result is 255
 
LDR20:	  MOV   LICHT,A   ; Save value
	  RET