Service manual

EPSON ELP-3500 Service Manual

1-16

Asynchronous Data Bus (ADB) Port

Features

This interface is provided on an optional cable (not on the projector).

❐

10 kbps serial bus

❐

Supports a keyboard or a mouse.

❐

Mini DIN 4-pin connector

❐

I/O data communication is enabled.

ADB port pin assignments

Figure 1-27. Mini DIN 4-pin Connector

Table 1-4. ADB Connector Pin Assignments

Pin Signal Functions

1 ADB I/O data bus. This is the open collector signal, which is pulled up

to +5 V through the 470

Ω

resistor on the main logic board.

2 POWER ON In Macintosh-type computers this pin is connected to pin 4, so

that using a key on the ADB keyboard activates this signal and

turns on the power. In other models this pin is not connected.

3 +5 V +5 V output

4 GND Ground

Procedure for driving the ADB port

An ADB device communicates with a Mac through a protocol specified by Apple

Computer Inc., which manipulates the HIGH/LOW level of ADB signals.

ADB port current limitations

Through the bus, a +5 V current is supplied to the ADB device. The total current

consumed by the device must not exceed 500 mA. (For example, the current

consumed by an ordinary mouse is approximately 20 mA.)