C M L 1 2 S D P 2 5 6
0 1 / 3 0 / 0 4
17
BUS_PORT
GND
1 2
D11/PA3
PA2/D10
3 4
D12/PA4
PA1/D9
5 6
D13/PA5
PA0/D8
7 8
D14/PA6
A0
9 10
D15/PA7
A1
11 12
A2
A10
13 14
A3
OE*
15 16
A4
A11
17 18
A5
A9
19 20
A6
A8
21 22
A7
A12
23 24
A13
WE*
25 26
A14
PE3/LSTRB*
27 28
A15
PE5/MODA
29 30
PE7/NOACC **
PE6/MODB
31 32
PE1/IRQ*
+5V
33 34
PE0/ XIRQ*
PE2/RW
35 36
RESERVED
PE4/ECLK
37 38
RESERVED
GND
39 40
RESET*
The
BUS_PORT
supports off-board memory devices
while the HCS12 is in expanded mode.
PA0/D8 - PA7/D15
High Byte Data Bus in Wide
Expanded Mode. Port A in Single Chip Mode.
A0 – A15
Latched Memory Addresses 0 to 15.
OE*
Memory Output Enable signal, Active Low. Valid
with ECLK and R/W high.
WE*
Memory Write Enable signal, Active Low. Valid
with ECLK high and R/W low.
RESET*
HCS12 active low RESET signal.
KEYPAD / PORT H
The KEYPAD / PORT H connector provides interface for the HCS12 port H or applying a
keypad such as the Axiom Mfg. HC-KP. When applied as a KEYPAD connector, the interface
is for a passive 4 x 4 matrix (16 key) keypad device.
1
PH0
2
PH1
3
PH2
4
PH3
5
PH4
6
PH5
7
PH6
8
PH7
This interface is implemented as a software key scan. Pins PH0-3 are
used as column drivers which are active high outputs. Pins PH4-7 are
used for row input and will read high when their row is high.
See the file
Key12Dx.ASM
for an example program using this
connector.
P_COM1 and P_COM2
1
1
6
TXD0
2
6
7
RXD0
3
7
8
4
4
8
9
GND
5
9
X
The
COM-1
port has a Female DB9 connector that interfaces to
the HCS12 internal SCI0 serial port via the U11 RS232
transceiver. It uses a simple 2 wire asynchronous serial
interface and is translated to RS232 signaling levels.
1,4,6 connected and 7,8 connected
JP1 will isolate the SCI0 RXD pin from the transceiver.
