BU9799KV Datasheet, PDF (6/28 Pages) Rohm – Standard LCD Segment Driver

BU9799KV MAX 200 segments (SEG50×COM4)
●Functional descriptions
○Command /Data transfer method
This device is controlled by 2-wire signal (SDA, SCL).
SDA
Datasheet
SCL
START condition
STOP condition
Figure 7. 2-SPI Command/Data transfer Format
It is necessary to generate START condition and STOP condition in 2wire serial interface transfer method.
Slave address
S01111100AC
Command
A
0
START condition
Command or data judgment bit
Acknowledge
Display Data
AP
STOP condition
Figure 8. Interface protcol
Method of how to transfer command and data is shown as follows.
1) Generate “START condition”.
2) Issue Slave address.
3) Transfer command and display data.
○Acknowledge
Data format is 8bits. After transfer of 8-bits data, Acknowledge bit is returned.
When SCL 8th =’L’ after transfer 8bit data (Slave Address, Command, Display Data), SDA outputs ’L’
When SCL 9th =’L’, SDA stops output function.
(Since SDA Output format is NMOS-Open-Drain, it can’t output ‘H’ level.)
If there is no need Acknowledge function, please input ‘L’ level from SCL 8th=’L’ to SCL 9th=’L’.
SDA
SCL
1-7
8
9
S
SLAVE ADDRESS ACK
START
condition
1-7
8
9
DATA
ACK
1-7
8
9
DATA
P
ACK
STOP
condition
Figure 9. Acknowledge timing
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23.Jan.2015 Rev.003