AK4183_06 Datasheet, PDF (13/17 Pages) –

ASAHI KASEI
[AK4183]
„ WRITE Operation Sequence (Figure 13)
The selection of channel input of AK4183 is determined by a command byte. The timing of the driver switch on is 18^th falling edge
of SCL regardless PD0 bit when accelerate command (A2= “0”) is sent. The accelerate command is to accelerate the timing of
desired driver SW ON to ensure that AK4183 needs more settling time. As for actually sampling is on the time of READ operation,
it becomes possible to take settling time long even when the impedance of the touch screen is large.
SCL
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
SDA
Address Byte
Command Byte
R/ W
100
1
0
0 CAD0 0
0
S A2
A1 A0 X1 PD0 MODE X2
0
START
Touch Driver SW
A2=0, PD0=0 or 1
A2=1, PD0=1
AK4183
ACK
AK4183
ACK _STOP
A2=1, PD0=0
I
II
III
IV
Figure 13 write operation and Driver SW timing
„ READ Operation Sequence (Figure. 14)
A/D conversion is synchronized with SCL. Sampling time is the one SCL clock period (SCL7↓∼ SCL8↓) on the end of writing
address byte and then hold. A/D conversion is held on the next 12 SCL period (except MASTER ACK) .The readout sequence is
that after command byte has been sent, AK4183 respond with acknowledge if the address matches. The MSB data byte will follow
(D11∼D4) then issued acknowledge by master. The LSB data byte (D3∼D0, followed four “0”) will be followed by NOT
acknowledge bit (NACK) from master in order to terminate the read transfer. The master will then issued STOP that ends read
operation or Repeated Start condition that keeps write or read operation. The master will issue Repeated Start Condition or START
condition followed by read operation again. AK4183 repeats A/D data updated [continuous read operation]. Master must issue
STOP condition after terminating the last read out of A/D data.
SCL
SDA
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
R/ W
100
1
0
0 ^CAD0 1
0 ^{D11 D10 D9}
D8 D7 D6 D5 D4
0 D3 D2 D1
D0
0
0
0
0
1
START
Address Byte
AK4183
ACK
Data Byte (MSB)
MASTER
ACK
Data Byte (LSB)
MASTER
NACK _{STOP or}
Repeated START
Touch Driver SW
A2=“0” or A2=“1” , PD0=“1”
Sampling
“H”
AD conversion
A2=“0”, PD0=“0”
A2=“1”, PD0=“0”
IV
V
VI
Figure 14 Read data Sequence
MS0500-E-00
13
2006/04