Motorola 68HC12B32 User Manual

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:

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

PS4

PS5

PS6

PS7

PP4

PP5

PP6

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.