AT42QT2161-MMU Atmel, AT42QT2161-MMU Datasheet - Page 42

• Manufacturer Part Number: AT42QT2161-MMU
• Description: IC TOUCH SENSOR 16KEY QFN M-MOD
• Manufacturer: Atmel
• Type: Capacitiver

Specifications of AT42QT2161-MMU

• Touch Panel Interface: 8, 2-Wire
• Number Of Inputs/keys: 16 Key, Slider
• Resolution (bits): 10 b
• Data Interface: I²C, Serial
• Voltage Reference: Internal
• Voltage - Supply: 1.8 V ~ 5.5 V
• Current - Supply: 1.14mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.8
8.9
42
Direction
GPIO
GPIOs
Typical Initialization and Usage
0
0
1
1
1
AT42QT2161
GPIO
PWM
X
X
0
0
1
Table 8-1.
By default, the dedicated GPIOs (GPIO1 – GPIO3) are set as inputs. Make sure to drive (set to
outputs) these GPIOs if not used, as floating pins may consume unnecessary current.
By default, shared GPOs are push-pull outputs driven low when not measuring.
Table 8-1
Figure 8-1 on page 43
1. After a reset/power-up, wait for CHANGE to go low, indicating the QT2161 has
2. Send all the setup parameters that need to be changed from the startup default values.
3. After setting up the QT2161, send a Calibrate command.
4. Read all status bytes once (address 2 to 6), to return the CHANGE line to an inactive
5. If CHANGE line goes low, perform a read of the required status byte. All the status
6. Process the received byte accordingly.
7. Check the reset bit in the general status byte (address 2). If it is a 1, go to step 2 to
8. Repeat steps 5, 6 and 7. Steps 5 and 6 are the continuous normal operating loop
initialized and is ready to communicate.
Drive all unused GPIOs to outputs, to prevent unnecessary increase in current
consumption.
state.
bytes that have changed need to be read, to ensure that the CHANGE line goes
inactive again.
resend all the setup parameters, as a reset has occurred. If it is a 0, proceed to the next
step.
sequence after initialization.
GPIO
Drive
X
X
X
0
1
shows a summary of the GPIO options, and the precedence of each setting.
GPIO Options
Wake
X
1
X
X
X
shows a typical example of communicating with the QT2161.
Input - read only in LP mode so CHANGE
CHANGE event possible in both modes
Input - read in LP and Sleep modes so
event possible only in LP mode
Dedicated GPIO Function
Output - PWM
Output - Gnd
Output - Vdd
Shared GPO Function
Output - PWM
Always output
Always output
Output - Gnd
Output - Vdd
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