Oki 3321, 3320 specifications LSI Optd Opck NPA2 Oprd Optxd Opclk

2.1.7Operation 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

OPTXD
77
OPCLK	Command
78		LED driver
	and Data
OPCLR-N
	latch
80
OPRXD
79
		+5V
		Switch
		controller

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.

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