AT42QT2120 Datasheet
Table Of Contents
- Features
- 1. Pinouts and Schematics
- 2. Overview
- 3. Wiring and Parts
- 4. I2C-compatible Communications (Comms Mode Only)
- 5. Setups
- 5.1 Introduction
- 5.2 Address 0: Chip ID
- 5.3 Address 1: Firmware Version
- 5.4 Address 2: Detection Status
- 5.5 Addresses 3 – 4: Key Status
- 5.6 Address 5: Slider Position
- 5.7 Address 6: Calibrate
- 5.8 Address 7: Reset
- 5.9 Address 8: Low Power (LP) Mode
- 5.10 Address 9 – 10: Toward Touch and Away from Touch Drift (TTD, ATD)
- 5.11 Address 11: Detection Integrator (DI)
- 5.12 Address 12: Touch Recal Delay (TRD)
- 5.13 Address 13: Drift Hold Time (DHT)
- 5.14 Address 14: Slider Options
- 5.15 Address 15: Charge Time
- 5.16 Address 16 – 27: Detect Threshold (DTHR)
- 5.17 Addresses 28 – 39: Key Control
- 5.18 Addresses 40 – 51: Pulse/Scale for Keys
- 5.19 Address 52 – 75: Key Signal
- 5.20 Address 76 – 99: Reference Data
- 6. Specifications
- Appendix A. I2C-compatible Operation
- Associated Documents
- Revision History
4
9634E–AT42–06/12
AT42QT2120
1.2 Pin Descriptions
1.2.1 20-pin SOIC/TSSOP
Table 1-1. Pin Listings (20-pin SOIC/TSSOP)
Pin
Name
(Comms)
Name
(Standalone) Type Description If Unused...
1
KEY8/
GPO6
OUT3 I/O
Comms mode: Key 8 / General-purpose output
Standalone mode: push-pull output for key 3
Leave open
2
KEY7/
GPO5
OUT2 I/O
Comms mode: Key 7 / General-purpose output
Standalone mode: push-pull output for key 2
Leave open
3
KEY6/
GPO4
KEY6 I/O
Comms mode: Key 6 / General-purpose output
Standalone mode: Key 6
Leave open
4
KEY5/
GPO3
KEY5 I/O
Comms mode: Key 5 / General-purpose output
Standalone mode: Key 5
Leave open
5
KEY4/
GPO2
KEY4 I/O
Comms mode: Key 4 / General-purpose output
Standalone mode: Key 4
Leave open
6
KEY3/
GPO1
KEY3 I/O
Comms mode: Key 3 / General-purpose output
Standalone mode: Key 3
Leave open
7
KEY2/
GPO0
KEY2 I/O
Comms mode: Key/slider/wheel 2 / General-purpose output
Standalone mode: Key 2
Leave open
8 KEY1 GUARD I/O
Comms mode: Key/slider/wheel 1
Standalone mode: Guard channel
Leave open
9 KEY0 PROX I/O
Comms mode: Key/slider/wheel 0
Standalone
mode: Proximity channel
Leave open
10 VSS VSS P Ground –
11 VDD VDD P Power –
12 MODE MODE I
Mode selection pin
Comms mode: connect to Vss
Standalone mode: connect to Vdd
–
13 SDA N/C OD
Comms mode: Serial Interface Data
Standalone
mode: Unused
Pull up to Vdd
14 RESET
RESET I Active low reset; has internal pull-up 60 k resistor Tie to Vdd
15 N/C PXOUT O
Comms mode: no connection
Standalone mode: open drain output for proximity channel
Leave open
16 SCL N/C OD
Comms mode: Serial Interface Clock
Standalone
mode: Unused
Pull up to Vdd
17 CHANGE N/C OD
Comms mode: Active low s
tate change interrupt (external
pull-up resistor needed)
Standalone mode: Unused
Pull up to Vdd
18
KEY11/
GPO9
OUT6 I/O
Comms mode: Key 11 / General-purpose output
Standalone mode: push-pull output for key 6
Leave open
19
KEY10/
GPO8
OUT5 I/O
Comms mode: Key 10 / General-purpose output
Standalone mode: push-pull output for key 5
Leave open
20
KEY9/
GPO7
OUT4 I/O
Comms mode: Key 9 / General-purpose output
Standalone mode: push-pull output for key 4
Leave open
I Input only I/O Input and output OD Open drain output P Ground or power