AK4186 Datasheet, PDF (22/33 Pages) Asahi Kasei Microsystems – Low Power Touch Screen Controller with I2C Interface

[AK4186]
■ Touch Screen Controller Control Sequence (Single Mode)
(1) Setup Sequence
In case of the single measurement mode, this touch panel configuration register sets the measurement mode of the
AK4186. Touch screen driver switches are turned ON at Driver ON mode (PD0 bit = “1”) on the rising edge of the 27th
SCL. It is possible to have longer tracking time even if the source of analog input impedance is high, because the actual
sampling is executed at the read operation. If a current measurement is made by the same setting of PD0 bit as the last
time, the setup sequence is unnecessary.
SCL
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}
SDA
Slave Address Byte
R/ W
100
1 0 0 CAD0 0 0
START
Touch Screen
Driver SW
PD0 =1
AK4186
ACK
Sub Address Byte
Register Addr = 01H
Data Byte
0
PA NEL
0
SLEEP SLEEP
1
0
0
0
A K 418 6
ACK
0 PD0 ₀
AK4186
ACK _STOP
PD0=0 “Off”
Figure 27. Setup operation and Driver SW timing
(2) Single Measurement Sequence
When the master send a READ command after sending a control register address for a measurement channel by a
WRITE operation, the AK4186 starts A/D conversion in single mode. This A/D conversion is synchronized with the
internal clock. The internal oscillator of the AK4186 is automatically powered up on the falling edge of 25th SCL after
writing the register address, and the AK4186 samples the analog input and completes A/D conversion after the rising
edge of 26th SCL. The master receives the first byte of serial data (D11-D4, MSB first), and generates an acknowledge.
Then the master receives the second byte of serial data (D3-D0, followed by four 0 bits). When the master continuously
reads ADC data, the master repeats read operation after generating an acknowledge. If the master does not generate an
acknowledge but generates stop condition instead, the AK4186 ceases continuous operation.
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 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
R/ W
1 0 0 1 0 0 ^CAD 0 0
0
START
Slave Address Byte
AK4186
ACK
Register Addr = 20H~28H
Sub Address Byte
R/ W
1 0 0 1 0 0 ^CAD 1
0
0 D11 D10 D9 D8 D7 D6 D5 D4 0 D3 D2 D1 D0 0 0 0 0 1
AK4186
ACK
START
Slave Address Byte
AK4186
ACK
Data Byte (MSB)
Master
ACK
Data Byte (LSB)
Master
ACK
STOP
OSCLK
PD0=“1”
“H”
Touch Screen
Driver SW
PD0=“0”
PENIRQN PD0=“0”
Sampling
AD conv.
ENABLE
“L”
Figure 28. Single Measurement operation and Driver SW timing
Sampling
AD conv.
ENABLE
MS1068-E-04
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2011/03