;   Keith Neufeld
;   05-Aug-2006
;
;   LogoChip library to configure the number of analog inputs, which
;   start on port A and work into port E (on the 4320) and port B:
;
;	A0, A1, A2, A3, A5, E0, E1, E1, B2, B3, B1, B4, B0
;
;   (PIC18F2220/2320/4220/4320 Datasheet, p. 4)
;
;   Lines set as analog inputs also function as digital outputs,
;   depending on the settings of their port's tristate register.  Lines
;   not set as analog inputs function as digital I/O.
;
;   The PIC sets all possible inputs to analog on powerup (Datasheet
;   p. 50), which the LogoChip firmware overrides to five (A0-3 and A5;
;   LogoChip Language Reference, p. 7).


constants [
    [ADCON $fc1]			;   port A control register
	[PCFG-MASK #00001111]		;	mask for port config bits
					;   Datasheet p. 214

]


to config-analog-lines :number
    if (:number < 0 or :number > 13) [	;   only 13 lines possible
	stop
    ]

    ;   Preserve high nybble and set low nybble to %1111 minus the desired
    ;   number of analog lines.
    ;
    ;   *ADCON = (*ADCON & !PCFG-MASK) | (PCFG-MASK - :number)
    write ADCON (((read ADCON) and (not PCFG-MASK)) or (PCFG-MASK - :number))
end