Sharp ER-A770 Service Manual download pdf (Page 49)

3-6. Extended I/O area

The addresses from F00000h to FFFFFFh are called an extended I/O

area. The ER-A770 uses the following addresses as the break ad-

dress register (BAR) for SSP.

• FFFF00h ∼ FFFFFFh

4. LCD display

The ER-A770 uses a 320 x 240 dot monochromatic LCD for the main

display and VGAC (MN89303A) for the display controller which is

connected to H8/510 in the ISA bus connection mode.

4-1. Block diagram

Here is the block diagram of the LCD and its allied components.

4-2. LCD panel

The LCD panel uses a dot-matrix liquid crystal module LM320153

with monochromatic STN and COFT backlight. The resolution is 320

x 240.

4-3. Display controller

Matsushita VGAC (MN89303A) is used for display controller.

VRAM is on the address space of the CPU and data can be written

on and read from it by every 128 KB of bank at the address C00000H

∼ C1FFFFH from the CPU side. VRAM consists of 4 banks.

4-4. LCD ON control

The LCD’s is bias power supply is controlled by the MN89303A termi-

nal LCDON to turn the LCD screen on and off.

The LCDON is at "L" at resetting +5V power is supplied to the LCD by

setting the expanded function control register bit5 of MN89303A to

"H" with software. The LCD screen isn’t turned on until +5V is sup-

plied.

4-5. Back light control

The back light is turned ON/OFF by the MN89303A terminal

BACKON. The initial value is "L" and the back light is off. By setting

the expanded function control register bit6 of MN89303A to "H", the

inverter unit is turned on.

4-6. Luminance and contrast adjustment

•

Luminance: Luminance is adjusted with an inverter which has dim-

ming function.

• Contrast: Contrast is adjusted by controlling the contrast adjust-

ment voltage (VCON) of the LM320153

5. Customer display

The ER-A770 can incorporate a UP-I16DP (display tube unit for the

UP-P16DP) for the customer display to carry out the same control as

for the pole display (UP-P16DP).

CPU

H8/510

RD#

WR#

SD0-15

SA0-16

IORD#

MEMRD#

IOWR#

MEMWR#

PHAI CLK

WAIT#

RAS/CAS

WE#

MD0-15

MA0-9

RAS/CAS

WE#

D0-15

A0-9

VRAM

DRAM:512KB

LD0-3

DCLK

LD0-3

DCLK

LCD (320X240)

BACKLIGHTVEE

BIAS

INVERTER

LCDON

BACKON

LCDWT

RFSH#

WAIT#

MPCA8

MN89303A

Fig. 7

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 88 89

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Sharp ER-A770 Service Manual Page 49

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