'
' A small test program to exercise the A/D functions on
' a 68HC12
'
' This file is written for the 68HC12 by Kevin Ross (kevinro@nwlink.com)
' It is written in SBASIC.
' To compile this file, you need to invoke the following commands:
'
' sbasic adtest.bas /cf000 /v0000 /m6812 > adtest.asm
' as12 adtest.asm
'
'
declare NewValue
declare CurrentChannel
'
' The following three variables are used as temporaries
' in the code. You must preserve them across function calls
'
declare i
declare j
declare k

include "regs12.lib"


'
' Single channel scan takes a single argument, which is the pin number to
' be read. It returns an eight sample average value. This function
' removes the arguement from the stack before returning.
'
SingleChannelScan:

	'
	' Perform a single channel A/D read cycle. By setting the
	' S8CM bit, the single channel is sampled 8 times consecutively
	' The low 3 bits determine which channel is going to be sampled
	' and is derived from the argument passed to this function.
	'
	' The 8 results are stored in registers ADR0 thru ADR7
	'
	' This provides a quick way of grabbing an average value
	'
	' Writing to ATDCTL5 will initiate the conversion
	'
	pokeb	atdctl5, %01000000 + pop()	' S8CM

	push j		' Save J across calls

	push i		' Save i across calls

	'
	' Wait for the SCF (Sequence Complete Flag) of ATDSTAT to be
	' set. When it is set, then the result registers are valid.
	'
	i = peek(tcnt)

	do
		j = peek(atdstat)
        loop while ( j AND $8000) = 0

	j = peek(tcnt)
	printx "Single Channel scan took " ; j - i ; " TCNT clocks "


	j = 0

	for i = 0 to 7
		j = j + peekb(adr0h + lshft(i))
	next
	j = j / 8

	' Restore i
	i = pop()

	' The original j is on the top of the stack. We really want to have
	' the average on the top of the stack, which is currently in the
	' j variable.
	'
	push j

	swap	' Now original j on top, average in second

	j = pop()	' Now average on top, j is restored

	' Returns with the average on the top of the stack

	return	pop()	

MultiChannelScan:

	push j
	push i
	'
	' Scan all 8 channels once then stop. The results are
	' stored in ADR0-ADR7
	'
	' Set atdctl5 for S8CM and MULT
	pokeb	atdctl5, %01010000

	j = peek(tcnt)
	' Wait for scan to be completed
	do loop while (peek(atdstat) AND $8000) = 0
	i = peek(tcnt)
	printx "MultiChannel took " ; i - j ; " TCNT clocks"

	i = pop()
	j = pop()

	return
main:
	' Turn off the COP
	pokeb copctl,0

	' Enable serial port
	poke  sc0bdh, 26	' Set for 19200 baud
	pokeb	sc0cr2,$0c	' Enable transceiver
	pokeb	tscr,$80	' Turn on the timer TCNT

	print
	print "****####****"
	print "adtest12 running"

	'
	' Set up the A/D converter
	'
	' Setup is for 8 channel mode, continuous scan, multi-channel
	' conversion, with results in ADR0 through ADR7
	'
	pokeb	atdctl2, %10000000	' ADPU is the power-up bit
					' Must be done FIRST

	'
	' Press the number ( 0 - 7 ) on the terminal to get a reading from
	' a particular channel. Press 'm' to get a multi-channel scan
	'
	do
	   i = inkey()
	   i = i AND $ff

	   if i >= '0' then
	      if i <= '7' then
     		' Switch channel number
		CurrentChannel = i - $30
		NewValue = USR(SingleChannelScan, CurrentChannel)
		printx "Single Channel 0x" ; CurrentChannel ; " = 0x" ; NewValue
              endif
     	   endif
	   '
	   ' If the user has pressed 'm', then do a multi-channel scan
	   '
	   if i = 'm' then
     		printx "Multi-Channel scan: "
		gosub MultiChannelScan
		for i = 0 to 7
			NewValue = peekb(adr0h + lshft(i))
			printx "Channel 0x" ; i ; " = 0x" ; NewValue
		next
           endif
	loop