2 – 15
LSI
OPTXD
OPCLK
OPCLR-N
OPRXD
77
78
80
OPTD
OPCK
NPA2
OPRD
Command
and Data
latch
LED driver
Switch
controller
+5V
79
A 2-byte (15 bits + 1 even parity bit) command signal (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.
2.1.7 Operation Panel
The clock synchronization OPCLK signal of the LSI is used to input the switch data and output
the LED data through the operation panel control LSI (IC1: BU5148S).
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