GPLB21C

6. FUNCTIONAL DESCRIPTIONS

6.1. ROM Area

LCD display buffer

( 40 bytes used )

Unused

I/O Port / Registers

CPU working SRAM

( 128 bytes )

$0000

$003F

$0040

$006F

$0070

$007F

$0080

$00FF

$0100

$01FF

Reserved

$1000

$10FF

$A000

$A7FF

$A800

$FFFF

Data SRAM

( 256 bytes )

Test program ROM

( 2K bytes )

Program ROM

( 22K bytes )

$7F00~$7FFF are mapping to SRAM $1000~$10FF

*Note : $XX00~$XXFF m apping to SRAM $1000~$10FF

in $0200~$7FFF only 256 Bytes available in SRAM

$0200~$7FFF

$0200~$02FF are mapping to SRAM $1000~$10FF

$0300~$03FF are mapping to SRAM $1000~$10FF

$XX00~$XXFF are m apping to SRAM $1000~$10FF

The data SRAM address map : ( 256 bytes )

*Note: $FFF2-$FFF7 are reserved for testing

6.2. Mask Options

6.2.1. 32K from Crystal / R-osc with prescaler

When the crystal mode is selected, the system time base, LCD

timing, and auto-strobe signal is generated form the 32.768KHz

crystal oscillator.

The R-osc option is provided to support system

timebase, LCD timing, and auto-strobe signal without 32.768KHz

crystal oscillator.

When the R-osc mode is selected, the signals

and timings will be generated from pre-scaler.

By programming

register ($007C), users can get a suitable clock (R-osc) to replace

the 32.768 KHz clock.

Bit-5 of register ($007A) can also turn off

this clock.

6.3. LCD Mapping and Specification

SRAM space ($00H - $3F) is allocated for LCD display buffer.

To

display a pattern on the LCD, the user simply writes the

corresponding bits as display buffer.

The following table shows

the mapping between LCD and display buffer.

SEG8 - 1

(b7 - b0)

SEG16 - 9

(b7 - b0)

SEG24 - 17

(b7 - b0)

SEG32 - 25

(b7 - b0)

SEG38 - 33

(b5 - b0)

COM1

07H

06H

05H

04H

03H

COM2

0FH

0EH

0DH

0CH

0BH

COM3

17H

16H

15H

14H

13H

COM4

1FH

1EH

1DH

1CH

1BH

COM5

27H

26H

25H

24H

23H

COM6

2FH

2EH

2DH

2CH

2BH

COM7

37H

36H

35H

34H

33H

COM8

3FH

3EH

3DH

3CH

3BH

The GPLB21C supports LCD's with the following characteristics:

Duty: 1/6 or 1/8

= VDD

= VDD * 3/4

= VDD * 2/4

= VDD * 1/4

VEE

= GND

© Generalplus Technology Inc.

Proprietary & Confidential

3

MAR. 08, 2005

Version: 1.0