BU97941FV_15 Datasheet, PDF (6/27 Pages) Rohm – Multifunction LCD Segment Driver

BU97941FV MAX 104 segments (SEG26×COM4)
●Function Description
○Command・Data Transfer Method
○3-SPI（3-wire Serial Interface）
This device is controlled by a 3-wire signal: CSB, SCL, SD.
First, Interface Counter is initialized with CSB=”H”.
Setting CSB = “L” enables SD and SCL inputs.
Each command starts with Command or data judgment bit (D/C) as MSB data,
followed by D6 to D0 (this is while CSB=”L).
Internal data is latched at the rising edge of SCL, then the data is converted to an 8-bit parallel data at the falling edge of
the 8th CLK.
When CSB changes from “L” to “H” and the data being transferred is less than 8 bits, command and data being
transferred will be cancelled.
To start sending command again, please set CSB to “L”. Then, be sure to input a 1-byte command .
Also, when DDRAM data becomes input state through RAMWR command, the device cannot accept command inputs.
In order to input again, please start up CSB.
If CSB is set to ”H”, the data input state is cancelled and if ”CSB” is set to ”L” again, command will be received.
1st byte Command
CSB
2nd byte Command
3rd byte Command
SCL
SD
D/C D6 D5 D4 D3 D2 D1 D0 D/C D6 D5 D4 D3 D2 D1 D0 D/C D6 D5 D4 D3 D2 D1 D0 D/C _D6
Figure 7. 3-SPI Data Transfer Format
○ Write and Transfer Method of Display Data
This device has display data ram of 26×4＝104bit.
The handling of display data with write and the handling of DDRAM data and Address and display are as follows:
1st Byte 2nd Byte
Command Command Command
10000011 00000000 10100000 _{a b c d e f g h i j k l m n o p …}
Address set
RAM Write
onwards
Display data
Binary 8-bit data is written to DDRAM. The starting address is set with the Address set command, and is automatically
incremented per 4bit data received.
Next, by transferring data, data can be written continuously to DDRAM.
(When continuously writing data to DDRAM, after writing to the final address 19h（SEG25）, address will return to 00h
(SEG0) through auto increment.)
DDRAM address
00
01
02
03
04
05
06
07
・・・ 17h
18h
19h
0
1
BIT
2
3
a
b
c
d
SEG
0
e
f
g
h
SEG
1
i
j
k
l
SEG
2
m
n
o
p
SEG
3
SEG
4
SEG
5
SEG
6
SEG
7
SEG
23
SEG
24
SEG
25
COM0
COM1
COM2
COM3
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10.Apr.2015 Rev.004