BU21049GUL Datasheet, PDF (6/26 Pages) Rohm – 4-wire Resistive Touch Screen Controller

BU21049GUL
Datasheet
●Host interface specification
The BU21049GUL operates as I2C slave device. The host processor transmit address byte after start condition when start
communication with the BU21049GUL. In case of operate convert function or write to register of the BU21049GUL, the host
processor transmit command byte after receive acknowledge of address byte. Communication with the BU21049GUL is
end when receive stop condition.
Address byte
Slave address for 2-wire interface is placed in the upper 7-bit of address byte and the last bit is READ/WRITE.
The upper 6-bit of slave address is fixed to “100000”, and the last bit of slave address is selected by “AD0” input.
Serial interface slave address byte
MSB
LSB
D7
D6
D5
D4
D3
D2
D1
D0
1
0
0
0
0
0
A0
R/W
Bit D1: A0
Slave address bit0 (AD0)
Bit D0: R/W
1=read (reading data)
0=write (writing data)
Command byte
The BU21049GUL operates depend on command byte. The host processor set CID (D7) to 1 when perform convert
function or set CID(D7) to 0 when perform register access..
Serial interface Command byte 1(CID=1)
MSB
LSB
D7
D6
D5
D4
D3
D2
D1
D0
1
CF
CMSK
PDM
STP
Bit D7: Command Byte ID
1= Command Byte 1(start conversion function according to CF(Bit D6-D3)
Bits D6-D4: CF
Convert function select as detailed the below.
BU21049GUL Convert function List
CF Description
0x0 Touch screen scan function: X, Y, Z1 and Z2 coordinates and converted.
0x1 NOP
0x2 Auxiliary input converted.
0x3 Reserved
0x4 Free scan function: Drivers status and input of A/D assignment by Host.
0x5 Calibration: Paramters which used dual touch detection calibrated.
0x6 NOP
0x7 NOP
0x8 X+, X- drivers status.
0x9 Y+, Y- drivers status.
0xA Y+, X- drivers status.
0xB NOP
0xC Touch screen scan function: X coordinate converted.
0xD Touch screen scan function: Y coordinate converted.
0xE Touch screen scan function: Z1 and Z2 coordinates converted.
0xF Reserved
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31.JAN.2012 Rev.001