BU97981KV-E2 Datasheet, PDF (16/50 Pages) Rohm – Multi-function LCD Segment Drivers

BU97981xxx Series MAX 196 segments (SEG49xCOM4)
Datasheet
Function Descriptions
Command and Data Transfer Method
3-SPI (3 wire serial interface)
This device is controlled by 3-wire signal (CSB, SCL, and SD).
First, Interface counter is initialized with CSB=“H”,
and CSB=”L” makes SD and SCL input enable.
The protocol of 3-SPI transfer is as follows.
Each command starts with Command or Data judgment bit (D/C) as MSB data,
and continuously in order of D6 to D0 are followed after CSB =”L”.
(Internal data is latched at the rising edge of SCL, it converted to 8bits parallel data at the falling edge of 8^th CLK.)
When CSB rise from “L” to “H”, and at this time sending commands are less than 8bit, command and data transfer are
canceled. To start sending command again, please fall CSB=”L” and send command continuously.
After sending RAMWR or BLKWR or GPOSET command, BU97981KV/MUV is in the RAM data input mode. Under this
mode, device can not accept new commands.
In this case, please rise CSB=”H” and fall CSB=”L”, after this sequence device released from RAM data input mode, and
can accept new command.
1st byte Command
2nd byte Command
3rd byte Command
CSB
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 15. 3-SPI Data Transfer Format
8bit data, sending after RAMWR command, are display RAM data
8bit data, sending after BLKWR command, are blink RAM data
SCL and SD can be set to “H” or cleared to “L” during CSB=”H”
www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111ï½¥15ï½¥001
16/46
TSZ02201-0A2A0D300110-1-2
10.Apr.2015 Rev.006