Sierra Video 503108 RS-232 - Manual (Page 11)

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Sierra Video Systems • P.O. Box 2462 • Grass Valley, CA 95945 • (530) 478-1000 • Fax (530) 478-1105
503108 RS-232 INTERFACE
Address D000. This is 2k byte of static RAM.
Address E000-FFFF. This is the EPROM which is
an 8K bytes 27C64.
A vertical interval pulse enters the card on pin 9S
(solder side), is inverted, and goes to the IRQ
input (pin 5) of the processor.
The board has a watch dog timer circuit (WDT)
that, should it time out, will automatically reset
the processor.
Power.
Low voltage AC (24 VCT) enters the board on
pins 25, 26, 27, 28. It is rectified by the diodes
D25-D32, filtered by C6, and is regulated to +5
volts by Q1, +12 volts by Q2, and -12 by Q3.
Diagnostics.
The front edge of the 503108 has four LEDs
which are used during start-up to display the
various steps the software runs through to check
the hardware. The following is a normal reset
sequence:
Flashing LED Description
ALL Processor is up and alive
LED4 EROM checksum failure
LED3 68HC11 internal RAM failure
LED2 External RAM failure
LED1 External port loopback failure
During operation the LEDs indicate the various
steps involved in processing control data as
follows:
LED1-4 Description
0010 Clear matrix command being executed.
0011 Waiting for vertical sync.
0100 Doing a bus output.
0101 Bus busy, waiting for strobe.
0110 Strobe occurred, waiting not BUSY.
0111 Battery RAM reintialized.
1000 Waiting to receive a character.
1001 Waiting to send a character.
When the processor is in an idle state the LEDs
will indicate 1000 described above.