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参数资料
| 型号： | AT42QT1111-AU |
| 厂商： | ATMEL CORP |
| 元件分类： | 速度传感器和接近开关 |
| 英文描述： | PROXIMITY SENSOR-CAPACITIVE, 0-5V, SQUARE, SURFACE MOUNT |
| 封装： | 7 X 7 MM, 1 MM HEIGHT, 0.80 MM PITCH, ROHS COMPLIANT, PLASTIC, MS-026ABA, TQFP-32 |
| 文件页数： | 11/50页 |
| 文件大小： | 637K |
| 代理商： | AT42QT1111-AU |
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9571B–AT42–08/10
AT42QT1111-MU/AT42QT1111-AU
4.8
Trigger Modes
4.8.1
Timed Trigger
In 11-key mode, The QT1111 can be configured to use the internal clock as a timed trigger. In
this case, the QT1111 is configured with a cycle period, such that each acquisition cycle starts a
specified length of time after the start of the previous cycle. If the cycle period is set to “0”, each
acquisition cycle starts as soon as the previous one has finished, resulting in the acquisition
cycles running back-to-back in a “free run” mode.
The use of a timed trigger, and the cycle period to be used, is set in the Device Mode setup byte
(see Section 7.4 on page 29).
4.8.2
Synchronized Trigger
Alternatively, the QT1111 can operate in “synchronized” mode. In this mode, SNS10K is used
as a SYNC pin to trigger key acquisition, rather than using the device’s internal clock. In this
case the maximum number of keys is reduced to 10.
The SYNC pin can use one of two methods to trigger key measurements, selectable via bit 4 of
the Device Mode setup byte (see Section 7.4 on page 29): Low Level and Rising Edge.
With the Low Level method the QT1111 operates in “free run” mode for as long as the SYNC pin
is read as a logical “0”. When the SYNC pin goes high, the current measurement cycle will be
finished and no more key measurements will be taken until the SYNC pin goes low again. The
low level trigger should be a minimum of 1 ms so that there is sufficient time for the device to
detect the low level.
With the Rising Edge method all enabled keys are measured once when a rising edge is
detected on the SYNC pin. This allows key measurements to be synchronized to an external
event or condition.
Note:
In SYNC mode a single acquisition burst is carried out for self-testing at start-up. No
further bursts occur unless triggered via the SYNC pin.
For example, the SYNC pin can be used by the host to synchronize several devices to each
other. This would ensure that only one of the devices outputs pulses at any given time and
signals from one QT1111 do not interfere with the measurements from another.
Another use for synchronizing to the rising edge is to steady the signals when the device is
running off a mains transformer with insufficient mains frequency filtering that is causing a 50Hz
or 60Hz ripple on Vdd. If the mains voltage is scaled down with a simple voltage divider and
connected to the SYNC pin, then the key measurement can be triggered by the rising edge
detected at a positive going zero-crossing. Note that in this case, each key signal will be taken at
the same point in the cycle, so Vdd will be the same at each measurement for a given key and
the signals will be steadier.
4.9
Guard Channel Option
The device has a guard channel option (available in all key modes), which allows one key to be
configured as a guard channel to help prevent false detection (see Figure 4-9 on page 20).
Guard channel keys should be more sensitive than the other keys (physically bigger or larger
Cs), subject to burst length limitations (see Section 4.11.2 on page 21).
With guard channel enabled, the designated key is connected to a sensor pad which detects the
presence of touch and overrides any output from the other keys using the chip’s AKS feature.
The guard channel option is enabled by the Guard Key setup byte (see Section 7.5 on page 30).
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相关代理商/技术参数 |
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|---|---|
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| AT42QT1111MU | 制造商:ATMEL 制造商全称:ATMEL Corporation 功能描述:QTouch? 11-key Sensor IC |
| AT42QT1111-MU | 功能描述:电容触摸传感器 QTouch 11 Key Touch Sensor IC RoHS:否 制造商:Microchip Technology 电源电压: 通道数量: 封装 / 箱体: 尺寸: 温度范围: |
| AT42QT1111-MU QS384 | 制造商:Atmel Corporation 功能描述:QTOUCH 11 KEY TOUCH SENSOR IC |
| AT42QT1244-AU | 功能描述:电容触摸传感器 QMatrix FMEA 24 Key Sensor IC RoHS:否 制造商:Microchip Technology 电源电压: 通道数量: 封装 / 箱体: 尺寸: 温度范围: |
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