13
COM1 SERIAL PORT
1
TXD0
2
6
RXD0
3
7
4
8
GND
5
9
The
COM-1
port has a Female DB9 connector that interfaces to
the HC12 internal SCI0 serial port. It uses a simple 2 wire
asynchronous serial interface.
Pins 1, 4, and 6 are connected for default handshake standards.
Pins 7 and 8 are connected for default handshake standards.
Handshake pins can be easily isolated and connected to I/O ports if necessary.
J2
1
T2IN
2
R2OUT
3
R2IN
4
T2OUT
The J2 connector (near COM1) contains spare RS232 translator inputs
and outputs. It can be used for implementing hardware handshaking on
COM1 if necessary.
BUS_PORT
The BUS_PORT supports off-board memory devices as follows:
GND
1 2
D11
D10
3 4
D12
D9
5 6
D13
D8
7 8
D14
A0
9 10
D15
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
CS0
CS1
27 28
CS2
CS3
29 30
CS4
CS5
31 32
IRQ
+5V
33 34
/P-SEL
/RW
35 36
CS6
E
37 38
CS7
GND
39 40
/ RESET
D8 - D15
High Byte Data Bus in Wide Expanded Mode and
Peripheral 8 bit data bus. Port A in Single Chip Mode.
A0 – A15
Memory Addresses 0 to 15.
/OE
Memory Output Enable signal, Active Low. Valid with ECLK
and R/W high.
CS0 – CS7
Peripheral chip selects, 16 bytes each located at
$200 - $27F hex, 8 bit access (narrow bus).
/WE
Memory Write Enable signal, Active Low. Valid with ECLK
high and R/W low.
IRQ
HC12 IRQ (PE1) Interrupt Input.
/RW
HC12 Read/Write (PE2) control signal.
E
HC12 ECLK (PE4) bus clock signal. Stretch should be enabled
in software.
/P-SEL
Selects Peripheral area, register following space, 8 bits
wide.
/RESET
HC12 active low RESET signal.
