BS812A-1/BS813A-1/BS814A-1/BS814A-2
BS816A-1/BS818A-2/BS8112A-3/BS8116A-3
Read or Write Control
Parallel Interface
SDA
TheꢀBS818A-2ꢀalsoꢀprovidesꢀaꢀparallelꢀinterfaceꢀ
functionꢀwhichꢀshowsꢀdirectlyꢀtheꢀkeyꢀstateꢀcondition.ꢀ
Whenꢀtheꢀparallelꢀoutputꢀtypeꢀisꢀselected,ꢀtheꢀtouchꢀ
keyꢀdataꢀreflectsꢀonlyꢀoneꢀkeyꢀstate,ꢀnotꢀmoreꢀkeys,ꢀ
atꢀtheꢀsameꢀtime.ꢀWhenꢀnoꢀtouchꢀkeyꢀisꢀpressed,ꢀ
BIN3~BIN0ꢀareꢀhigh.ꢀWhenꢀanyꢀkeyꢀisꢀpressed,ꢀ
BIN3ꢀmustꢀoutputꢀaꢀlowꢀtoꢀwakeꢀupꢀtheꢀmasterꢀwhileꢀ
BIN2~BIN0ꢀreflectꢀwhichꢀkeysꢀareꢀpressedꢀasꢀshownꢀ
inꢀtheꢀfollowingꢀtable.
SCL
1
2
7
8
9
R/W
0: Write
1: Read
Acknowledge
SDA
SCL
1
2
7
8
9
ACK
0: Acknowledge
Pressed key BIN3
BIN2
BIN1
BIN0
1: No acknowledge
No key
Key1
Key2
Key3
Key4
Key5
Key6
Key7
Key8
1 (high)
1
1
1
1
1
0
0
0
0
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
Slave Busy
0 (low)
Afterꢀaꢀdateꢀbyteꢀ(8bit+ACK)ꢀisꢀtransmitted,ꢀtheꢀslaveꢀ
deviceꢀisꢀbusyꢀwithꢀprocessingꢀtheꢀreceivedꢀdata(ꢀ
slaveꢀbusy)ꢀandꢀcannotꢀreceiveꢀtheꢀnextꢀdataꢀbyte.ꢀAtꢀ
thisꢀtimeꢀtheꢀSCLꢀlineꢀisꢀpulledꢀdownꢀandꢀtheꢀmasterꢀ
canꢀcontinueꢀtoꢀtransmitꢀtheꢀdataꢀuntilꢀtheꢀSCLꢀlineꢀisꢀ
pulledꢀhighꢀagain.
0
0
0
0
0
0
0
SDA
SCL
1
2
7
8
9
BUSY
I2C Interface
•ꢀ Read:
SDA
START and STOP Conditions:
1
2
3
4
5
6
7
8
9
SCL
BUSY
SDA
•ꢀ Write:
SDA
SCL
SCL
1
2
3
4
5
6
7
8
9
START
STOP
BUSY
Slave Address
AfterꢀtheꢀSTARTꢀsignal,ꢀaꢀ7-bitꢀslaveꢀaddressꢀwillꢀbeꢀ
transmitted.ꢀTheꢀslaveꢀaddressꢀisꢀ0x50.
SDA
SCL
1
2
7
8
9
Slave
Address(7bit)
Read Touch-key Status Data Register
ReadꢀtheꢀtouchꢀkeyꢀstatusꢀdataꢀstructureꢀofꢀtheꢀBS8112-3ꢀorꢀBS8116A-3.
NO ACK
A
C
K
A
C
K
A
C
K
Slave
Address
Slave
Address
W
0x08
0x09
KeyStatus0
KeyStatus1
Stop
Start
Start
Start
Start
R
R
NO ACK
Stop
A
C
K
A
C
K
A
C
K
Slave
Address
Slave
Address
W
NO ACK
Stop
A
C
K
A
C
K
A
C
K
A
C
K
Slave
Address
Slave
Address
W
KeyStatus1
0x08
KeyStatus0
Start
Start
R
Rev. 1.32
10
January 19, 2016
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
