REM     ADC control program.
REM     This program shows how to access the MC145050 Via the Printer Port.
REM     Replace the main body of this program to do what you want.
REM     MFL'94

REM Define constants for use latter

CONST power = &H70
CONST clock = &H4
CONST cs = &H2
CONST eoc = &H40
CONST addressbit = &H8
CONST datamask = &H80
CONST BIT0 = 1
CONST BIT1 = 2
CONST BIT2 = 4
CONST BIT3 = 8
CONST outputaddress = &H378: REM lpt1
CONST inputaddress = &H379


REM initialise port give power and cs hi.
OUT outputaddress, power OR cs

REM Your code goes here. E.G.

nexttosample = 0: REM Use this variable to specify which channel is next to be converted.
REM                     Note 0-10 are the input channels and 11,12,13 are internal references, Vref,Vref/2,0V

GOSUB SAMPLE: REM Dummy Read to set address.

FOR j = 1 TO 14
	nexttosample = j
	GOSUB SAMPLE
	PRINT Value
NEXT

REM Power Down.
OUT outputaddress, 0

STOP

REM now read in a sample... This is the Subroutine that does it all
REM Order of events...
REM Wait for EOC.       Make sure its ok to read the ADC.
REM Chip Select low.
REM Output the address MSB first onto the ADDR pin of the ADC
REM Read in the result of the last conversion.
REM     and put it in the LSB of the Value read in.
REM Clock the ADC.
REM Move on to next bit of address. when past the end of the real 4bit address all zero's are output.
REM Repeat address, data and clock loop for all data bits (10)
REM Chip select HIGH.   This with the clocked data transfer has started the next conversion on the channel specified in the address sent.
REM Convert Value into Volts.   Note that BUSY is inverted so data bits have to be inverted before thay are used.

SAMPLE:

Value = 0
nextaddress = nexttosample AND &HF

REM wait for EOC
WHILE (INP(inputaddress) AND eoc) = 0
WEND

REM before clock data put the cs lo.
OUT outputaddress, power

FOR i = 1 TO 10
	REM output the address
	OUT outputaddress, power OR (nextaddress AND addressbit)

	REM read in data bits MSB first.
	Value = ((INP(inputaddress) AND datamask) / 128) OR (Value * 2)

	REM rising edge of clock...
	OUT outputaddress, clock OR power OR (nextaddress AND addressbit)

	REM Move to next bit of address, if past the end zeros outputed.
	nextaddress = nextaddress * 2
NEXT i

REM finished therefore cs to hi.  Therefore start next conversion.
OUT outputaddress, power OR cs

REM convert to volts
Value = (Value XOR &H3FF) AND &H3FF
Value = Value * 2.5 / 1024

RETURN