at42qt1070 ATMEL Corporation, at42qt1070 Datasheet - Page 15

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

4. I
4.1
4.1.1
4.1.2
4.2
4.3
4.3.1
9596A–AT42–10/10
2
C-compatible Communications (Comms Mode Only)
I
I
Data Read/Write
2
2
C-compatible Protocol
C-compatible Address
Protocol
Signals
Writing Data to the Device
The I
page
See
The I
A third line, CHANGE, is used to signal when the device has seen a change in the status byte:
There is one preset I
The sequence of events required to write data to the device is shown next.
Table 4-1.
Key
S
SLA+W
A
MemAddress
Data
P
• SDA - Serial Data
• SCL - Serial Clock
• CHANGE: Open-drain, active low when any capacitive key has changed state since the last
1. The host initiates the transfer by sending the START condition
2. The host follows this by sending the slave address of the device together with the
I
pulled up with an external resistor. If the status bytes change back to their original state
before the host has read the status bytes (for example, a touch followed by a release), the
CHANGE line is held low. In this case, a read to any memory location clears the CHANGE
line.
2
Section A on page 31
C-compatible read. After reading the two status bytes, this pin floats (high) again if it is
2
2
18) and supports multibyte reads and writes. The maximum clock rate is 400 kHz.
WRITE bit.
C-compatible interface requires two signals to operate:
C-compatible protocol is based around access to an address table (see
Description of Write Data Bits
S
2
C-compatible address of 0x1B. This is not changeable.
SLA+W
for an overview of I
A
Host to Device
MemAddress
Description
START condition
Slave address plus write bit
Acknowledge bit
Target memory address within device
Data to be written
Stop condition
2
C-compatible bus operation.
A
Data
Device to Host
AT42QT1070
A
P
Table 5-1 on
15