BU21026MUV Datasheet, PDF (11/23 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21026MUV
Write Protocol
An command write is started in BU21026MUV when the master sends the start condition, the slave address of
BU21026MUV, and zero in bit 0( 8^th bit) for writing, as shown in Table 1. If the slave address is matched with its own,
BU21026MUV issues an acknowledge to the master. When the master receives the acknowledge from BU21026MUV, the
master send the command byte. When BU21026MUV received next 8 bits, it issues another acknowledge to the master.
After the acknowledge is received by the master, the master sends the stop or repeated start condition for ending write.
START
SCL
1234567
STOP or
Repeated START
Driving
Acquisition
Conversion
8 9 10 11 12 13 14 15 16 17 18
Address Byte
Command Byte
SDA
1 0 0 1 0 AD1 AD0 0 0 C3 C2 C1 C0 O3 O2 O1 O0 0
SLAVE ADDR
R/WB ^ACK
FROM
BU21025
ACK
FROM
BU21025
Figure 1. Write Protocol
If a receiving command in BU21026MUV is not the software reset or setup, BU21026MUV starts driving screen voltage
when C0 is latched by rising edge of SCL. Next, if the received type of operation code is measurement, BU21026MUV
starts acquisition in A/D converter when next falling edge of SCL. BU21026MUV stops acquisition and starts A/D conversion
when BU21026MUV receive the stop or repeated start condition.
When BU21026MUV receives a command other than software reset during the A/D conversion, the command is ignored.
And if the command is ignored, BU21026MUV doesn’t return an acknowledge at the ACK timing behind the command byte.
(18^th timing in Figure. 1)
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TSZ22111 • 15 • 001
11/19
TSZ02201-0L5L0FF00890-1-2
4.Aug.2016 Rev.001