11
PORTS AND CONNECTORS
LCD_PORT
The LCD_PORT interface is connected to the data bus and memory mapped to locations 270
– 27F hex assigned to CS7. For the standard display, address 270 is the Command register,
address 271 is the Data register.
The interface supports all OPTREX
DMC series displays in 8 bit bus mode with up to 80
characters and provides the most common pinout for a dual row rear mounted display
connector. Power, ground, and Vee are also available at the LCDPORT-1 connector.
+5V
2
1
GND
A0
4
3
LCD-Vee
LCD1
6
5
/RW
D9
8
7
D8
D11 10
9
D10
D13 12 11 D12
D15 14 13 D14
Command Register:
$270
Data Register:
$271
LCD-Vee is supplied by U13 and is adjusted by the R18
Potentiometer (adjustable resistor).
See the file
KEYLCD12.ASM
for an example program using this
LCD connector.
LCD3 2
1
LCD2
4
3
LCD4
Additional lines can be used as enables for larger panels and
are mapped as:
LCD2 = $274 & $275
LCD4 = $27C & $27D
LCD3 = $278 & $279
KEYPAD
1
PS4
2
PS5
3
PS6
4
PS7
5
PP4
6
PP5
7
PP6
8
PP7
The KEYPAD connector is a passive 8-pin connector that can be used to
connect a 4 x 4 matrix (16 key) keypad device. The connector is mapped to
the HC12 I/O ports S and P. This interface is implemented as a software
keyscan. Pins PS4-7 are used as column drivers which are active low
outputs. Pins PP4-7 are used for row input and provide an idle hi condition
with internal pull-ups to provide active key detection under software control.
See the HC12 Technical Reference Manual for a full description of these pins and the file
KEYLCD12.ASM
for an example program using this connector.
