at42qt2100 ATMEL Corporation, at42qt2100 Datasheet - Page 20

• Manufacturer Part Number: at42qt2100
• Description: Qtouch Touch Sensor Ic
• Manufacturer: ATMEL Corporation

5. SPI Commands
5.1
5.2
5.2.1
5.2.2
20
Introduction
“Normal Exchange” Mode
AT42QT2100
Introduction
Host Data
Each communication exchange between the QT2100 and the host device consists of 3 bytes
transmitted each way. The host controls the clock signals and the timing of the exchange.
The data sent by the host indicates the command mode and the device settings where
appropriate. There are four command modes, selectable through bits 5 – 7 of the first byte
(byte 0, Req bits):
The device settings sent by the host in its three command bytes becomes effective
immediately after all three bytes are received by the QT2100. The response to these three
bytes is three data bytes containing key detection information.
The “Normal Exchange” mode (Req = 000) is the normal mode for communication between
the host and the device. Data is sent every time an SPI communication occurs in “Normal
Exchange” mode. If one of the other commands is sent by the host, the corresponding
response will be sent during the subsequent 3-byte exchange.
This “Normal Exchange” response forms the default (start-up) QT2100 data.
In “Normal Exchange” mode (Req = 000) the host sends the 3-byte data in
Table 5-1.
Note:
• “Normal Exchange” mode (Req = 000)
• “Custom Threshold” command mode (Req = 100)
• “Send Signal” command mode (Req = 001)
• “Device Version” command mode (Req = 010)
Host
Byte
0
1
2
Bits labelled “0” should not be altered
“Normal Exchange” Mode – Host Command Bytes
7
0
Req = 000
Resolution
6
MOD
5
PROX
CalW
DI
4
Bit
CalK
SLD
LPB
3
2
Cal Key Num
LP Mode
Table
AKS
1
9554CX–AT42–11/11
5-1.
0