'
' A small test program to exercise the PWM functions on
' a 68HC912B32
'
' 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 /c8000 /v0000 /m6812 > adtest.asm
' as12 adtest.asm
'
declare i

include "regs12.lib"

main:
	' Turn off the COP
	pokeb copctl,0

	' Enable serial port
	poke  sc0bdh, 26	' Set for 19200 baud
	pokeb	sc0cr2,$0c	' Enable transceiver

	print
	print "****####****"
	print "pwmtest running"

	' Set the concatenate PWM channel bits so we have channels 0 and 1 acting
	' as 8 bit counters, and channels 2/3 acting as a single 16-bit counter
	'
	' There are two independent clocks on the PWM. Clock A and Clock B.
	' The low 6 bits of PWCLK set the prescalar values (3 bits each).
	' ClockA is going to run at full speed. ClockB is to be divided by 4
	'
	pokeb PWCLK, $82

	'
	' PWPOL is the Clock Select and Polarity control register. Clock A
	' runs channels 0 and 1, and CLOCK B is going to run channels 2 and 3
	' Polarities are set so that the signal is low at the start of the
	' cycle, and flips high when the duty count is reached on channel 0.
	'
	' Channel 2/3 is set to be high at the start, and go low at the end
	' of the duty period.
	'
	pokeb PWPOL, $0C

	' For now, we will assume all of the prescalars should be set to zero
	pokeb pwscal0, $0
	pokeb pwscal1, $0

	' Lets setup a 40khz signal on the 8-bit PWM channel 0 with a 50% duty cycle.
	' If you do the math, 8mhz/40k turns out to be 200,
	' which means that our period is 200 clocks. If you check the documentation,
	' it turns out that the correct value is 200 - 1 because of the way that
	' PWPER is compared in left aligned mode.
	'

	pokeb	pwper0, 200 - 1
	pokeb	pwdty0, 100 - 1

	' Now setup channel 2/3 with a 20 millisecond period, and a 1.52 millisecond duty
	' period. This should center a servo motor. 1.52ms / 500ns = 3040
	'
	poke	pwper2,40000 - 1
	poke	pwdty2,3040 - 1

	' Now enable channel 0 and channel 2/3 in the PWEN register. Due to a bug in the
	' XC and previous versions of the B32, you need to turn on both channel 2 and 3
	' to get this to work.

	pokeb	pwen, $0D

	do
	   i = inkey()
	   i = i AND $ff


	loop