Atmel QTouch Library User Guide

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Libraries for AVR microcontrollers include both acquisition methods. Libraries for ATSAMmicrocontrollers include only QTouch acquisition method.QTouch acquisition methodThe QTouch acquisition method charges an electrode of unknown capacitance to a knownpotential. The resulting charge is transferred into a measurement capacitor (Cs). The cycle isrepeated until the voltage across Cs reaches a voltage Vih. The signal level is the number ofcharge transfer cycles it took to reach that voltage. Placing a finger on the touch surfaceintroduces external capacitance that increases the amount of charge transferred each cycle,reducing the total number of cycles required for Cs to reach the voltage. When the signal level(number of cycles) goes below the present threshold, then the sensor is reported to be indetected.QTouch acquisition method sensors can drive single or multiple keys. Where multiple keys areused, each key can be set for an individual sensitivity level. Keys of different sizes and shapescan be used to meet both functional and aesthetic requirements.NOTE: It is recommended to keep the size of the keys larger than 6mmx6mm to ensure reliableand robust measurements, although actual key design requirements also depend on panelthickness and material. Refer to the ATMEL Capacitive touch sensor design guide for details.QTouch acquisition method can be used in two ways• normal touch contact (i.e. when pressing buttons on a panel), and• high sensitivity proximity mode (i.e. when a panel lights up before you actually contact it).Figure 5-2 : QTouch AcquisitionQTouch circuits offers high signal-to-noise ratio, very good low power performance, and theeasiest sensor layout.Sensor schematics for a QTouch acquisition method design148207K-AT42-09/11
SamplingcapacitorSNSKPB1RsElectrodeMicrocontrollerUsed for touchapplicationCsPC1SNSTypical Rs- 1kvalues: Cs- 22nF----------------Port requirements:SNS: generic I/O pinSNSK: generic I/O pinRs- Series resistor, Cs – Sample capacitor, PB1- PortB bit1, and PC1- PortC bit1Figure 5-3 : Schematics for a QTouch acquisition method designQMatrix acquisition methodQMatrix devices detect touch using a scanned passive matrix of electrode sets. A single QMatrixdevice can drive a large number of keys, enabling a very low cost-per-key to be achieved.Figure 5-4 : QMatrix Acquisition methodQMatrix uses a pair of sensing electrodes for each channel. One is an emitting electrode intowhich a charge consisting of logic pulses is driven in burst mode. The other is a receive electrodethat couples to the emitter via the overlying panel dielectric. When a finger touches the panel thefield coupling is changed, and touch is detected. The drive electrode (or drive line) used for15
Page 1: Atmel QTouch LibraryUser GuideSuppo
Page 4: 5.6.11.6.1 Debug Support in the sam
Page 7 and 8: 6.3.16.21 touch_info_t ............
Page 12 and 13: • ARM: refers to a device in the
Page 16 and 17: QMatrix charge transfer is labeled
Page 18 and 19: Maximum ON DurationIf an object uni
Page 20 and 21: Setting Variable name Data Type Uni
Page 22 and 23: Guard ChannelGuard channel in Qtouc
Page 24 and 25: 7 AKS groups are supported by the l
Page 26 and 27: Data structuresThis section lists t
Page 28 and 29: The signal gain for each sensor is
Page 30 and 31: • This function can be called any
Page 32 and 33: unit16_t qt_measure_sensors( uint16
Page 34 and 35: Channel NumberingChannel numbering
Page 36 and 37: qt_reset_sensing()qt_enable_xxx()qt
Page 38 and 39: Port AAll SNSK pinsterminatedon thi
Page 40 and 41: Example:Pins A0 ,A3 and A5 of PORT
Page 42 and 43: Channel 47 N/A N/A N/A N/A N/A X7Y5
Page 44 and 45: channel 0channel 1channel 2channel
Page 46 and 47: Disabling and Enabling of Pull-up f
Page 48 and 49: ‣ Recommended threshold should be
Page 50 and 51: QMatrix acquisitionmethod libraries
Page 52 and 53: definition is not required.QT_NUM_C
Page 54 and 55: SNS1 and SNSK1 pins usethe same por
Page 56 and 57: • It is recommended to disable PU
Page 58 and 59: Table 4 :List of configurable param
Page 60 and 61: Number ofchannels requiredfor the a
Page 62 and 63: 2. The above definitions should be
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NUM_Y_LINES_ROTOR_SLIDER_QT_MAX_NUM
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has Four Comparators (AC0A , AC1A ,
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Note: When using the IAR IDE / comp
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Figure 5-11: Selecting the right co
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SNS1 - SNSK1 & SNS2 -SNSK2QT_NUM_CH
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Selecting the right configurationTh
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Figure 5-20 : Specifying QMatrix ac
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Debug Support in Example applicatio
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Support for different compiler tool
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Maximum number of rotor / sliders s
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Tips on pin assignments for the sen
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ATtiny88)v1g1s2(ATtiny461,ATmega16a
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X0,X1,X2,X3 are on PB0,PB1,PB2,PB3N
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1. The channel numbers are allocate
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SNSK_array[1][1]=0x00; (SNSK odd ma
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SNSK_array[1][0]=0x14; (SNSK even m
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Figure 5-28: New Design Sensors in
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Figure 5-31: Selecting the MCU for
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Figure 5-34: Selecting the SNS and
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2. QTOUCH_STUDIO_MASKS needs to be
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Figure 5-38: Selecting New Design3.
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Figure 5-42: Start window of the co
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Figure 5-45: Selecting the X,YA,YB,
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The code can be copied using the
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ApplicablereleaseQTouch libraries v
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Device Specific LibrariesIntroducti
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Table 8 Compiler tool chains suppor
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maintains the States of QMatrix, QT
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equired as shown in the case A of F
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Figure 37 QMatrix method schematicQ
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Figure 39 QMatrix API Flow diagram
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CAT Module Pin NameCSA0CSB0CSA1CSB1
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The QTouch method acquisition using
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Host Application codeUsing the init
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Frozen Stop Stop Run Run Run Run On
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Figure 45 Raw acquisition mode API
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Figure 46 GNU Example project usage
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the QTouch Library as QMatrix data
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TOUCH_STATUS_CHANGE 0x0002u Status
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sensor_type_tEnumerationUsesensor_t
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OUT_OF_TOUCHIN_TOUCHCurrently the a
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num_channel_signals uint8_t Length
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touch_at_statusstructureInput / Out
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UseData structure which holds the R
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variable to the Touch library. The
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structure.p_qta_config touch_qt_con
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p_touch_sensor_param touch_qm_param
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current_time_ms touch_time_t Curren
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touch_ret_t touch_qt_sensor_config(
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touch_qt_sensors_calibratetouch_ret
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touch_qt_get_libinfotouch_ret_t tou
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• This API updates the configurat
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Rule Rule Description Advisory/Requ
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VCCPA0No ConnectionPA1PA2ATtiny20PA
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QTouch Library configuration parame
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Recommended setting.Table 19 QTouch
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Figure 51 Schematic overview of QTo
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QTouch Library configuration parame
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Devices supportedThe list of differ
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• The channel number is derived f
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MISRA Compliance ReportThis section
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May 2010Ver 4.2July 2010Ver 4.3Jan
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Atmel QTouch Library User Guide

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