Operation Panel - Oki Microline 3320 Maintenance Manual

2.1.7 Operation Panel

The clock synchronization OPCLK of LSI is used to input the switch data and output the LED
data through the operation panel control LSI (IC1: BU5148S).
LSI
OPTD
OPCK
NPA2
OPRD
A 2-byte (15 bits + 1 even parity bit) command (OPTXD) is transmitted to the LSI (BU5148S)
in synchronization with the OPCLK signal. The LSI decodes this command and when it is found
to be legal, returns a 2-byte command response back to the LSI which includes data on Switch
information, LED status, receive command ACK/NAK and 1 odd parity bit.
Any transmission errors found cause the command to be reissued after the transmission of the
OPCLR-N signal.
OPTXD
77
OPCLK
Command
78
and Data
OPCLR-N
latch
80
OPRXD
79
LED driver
Switch
controller
2 – 15
+5V