Epson Elp-3500, Service Manual, Page: 23 / 114

EPSON ELP-3500 Service Manual
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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.)
3 4
2 1