Down Counter using HCS12 in Assembly Language

The objective of this project is to utilize the 7-segments display and DIP switch interface with the HCS12 in the Dragon 12-plus.

Hardware Configuration

DDR Table

DDRH: DIP Switch Input

PH7	PH6	PH5	PH4	PH3	PH2	PH1	PH0	HEX
							SW1
X	X	X	X	X	X	X	0	$00

DDRB: 7-segments display output

PB7	PB6	PB5	PB4	PB3	PB2	PB1	PB0	HEX
Dp	g	f	e	d	c	b	a
1	1	1	1	1	1	1	1	$FF

DDRP: 7-segments output

PP7	PP6	PP5	PP4	PP3	PP2	PP1	PP0	HEX
X	X	X	X	1	1	1	1	$0F

DR Table

PTH: DIP switch (ACTIVE HIGH)

CONDITION	PH7	PH6	PH5	PH4	PH3	PH2	PH1	PH0	HEX
								SW1
Switch On	X	X	X	X	X	X	X	1	$01

PORTB: 7-segments display (COMMON CATHODE)

CONDITION	PB7	PB6	PB5	PB4	PB3	PB2	PB1	PB0	HEX
	Dp	g	f	e	d	c	b	a
0	0	0	1	1	1	1	1	1	$3F
1	0	0	0	0	0	1	1	0	$06
2	0	1	0	1	1	0	1	1	$5B
3	0	1	0	0	1	1	1	1	$4F
4	0	1	1	0	0	1	1	0	$66
5	0	1	1	0	1	1	0	1	$6D
6	0	1	1	1	1	1	0	1	$7D
7	0	0	0	0	0	1	1	1	$07
8	0	1	1	1	1	1	1	1	$7F
9	0	1	1	0	1	1	1	1	$6F

PTP: 7-segments display (COMMON CATHODE)

CONDITION	PP7	PP6	PP5	PP4	PP3	PP2	PP1	PP0	HEX
					DSP4	DSP3	DSP2	DSP1
DSP1 ON	X	X	X	X	1	1	1	0	$0E
DSP2 ON	X	X	X	X	1	1	0	1	$0D

MASKING TABLE

PH7	PH6	PH5	PH4	PH3	PH2	PH1	PH0	HEX
							SW1
0	0	0	0	0	0	0	1	$01