at42qt1070 ATMEL Corporation, at42qt1070 Datasheet - Page 31

• Manufacturer Part Number: at42qt1070
• Description: Qtouch 7-channel Sensor Ic
• Manufacturer: ATMEL Corporation

Appendix A.
A.1
A.2
A.3
9596A–AT42–10/10
Interface Bus
Transferring Data Bits
START and STOP Conditions
I
2
C-compatible Operation
The device communicates with the host over an I
an overview of the bus; more detailed information is available from www.i2C-bus.org. Devices
are connected to the I
to Vdd via pull-up resistors. The bus drivers of all I
type. This implements a wired “AND” function that allows any and all devices to drive the bus,
one at a time. A low level on the bus is generated when a device outputs a zero.
Figure A-1.
Each data bit transferred on the bus is accompanied by a pulse on the clock line. The level of the
data line must be stable when the clock line is high; the only exception to this rule is for
generating START and STOP conditions.
Figure A-2.
The host initiates and terminates a data transmission. The transmission is initiated when the
host issues a START condition on the bus, and is terminated when the host issues a STOP
condition. Between the START and STOP conditions, the bus is considered busy. As shown in
Figure
when the SCL line is high.
A-3, START and STOP conditions are signaled by changing the level of the SDA line
SDA
SCL
I
Data Transfer
2
C-compatible Interface Bus
SDA
SCL
Device 1
2
C-compatible bus as shown in
Device 2
Data Stable
Device 3
Data Change
2
C-compatible bus. The following sections give
2
C-compatible devices must be open-drain
Data Stable
Figure
Device n
A-1. Both bus lines are connected
R1
Vdd
AT42QT1070
R2
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