BU21049GUL Datasheet, PDF (9/26 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21049GUL
Datasheet
WRITE CYCLE
The 7-bit slave address is placed in the upper of address byte and Read/Write bit is in the LSB. The BU21049GUL issue an
acknowledgement after address byte if access is correct. After received the acknowledgement, HOST can send command
byte. When HOST received an acknowledgement of command byte from BU21049GUL, HOST continuously sends a write
data byte or issues a STOP condition.
S: START condition P: STOP condition A: ACK N: NACK
READ CYCLE
The LSB of address byte is READ bit. The BU21049GUL send back data byte followed by an acknowledge at read mode.
The send back data is conversion result or register value. (It’s depend on last command byte)
HOST needs to resend conversion command with setting “CMSK=1” if HOST read register value before read conversion
result. BU21049GUL send back next data byte if BU21049GUL receive the acknowledge from HOST after sending data
byte. HOST finish read access by issuing a START condition (or STOP condition) followed by a not-acknowledge(NACK)
when HOST received last data byte.
S: START condition P: STOP condition A: ACK N: NACK
SCL STRETCH
If HOST read conversion result while BU21049GUL is operating conversion, the BU21049GUL notify HOST by
SCL_STRETCH function.(*1) The SCL_STRECH is released when conversion function was finished.
SCL
SDA
STATU
S
1
0
0
0
0
0
1
Slave address & Read cycle
Convert function is running
(*1)Force SCL to “L” after ACK of slave address.
A
C
D7 D6
K
finish
(idle)
Stretch(SCL=L)
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TSZ02201-0Y1Y0F300010-1-2
31.JAN.2012 Rev.001