Atmel QTouch Library User Guide

The signal gain for each sensor is controlled by circuit parameters as well as the burst length.The burst length is simply the number of times the charge-transfer (‘QT’) process is performed ona given sensor. Each QT process is simply the pulsing of an X line once, with a corresponding Yline enabled to capture the resulting charge passed through the sensor’s capacitance Cx.The QMatrix acquisition method library exports a variable of this type which can be accessed toset the burst length for each of the QMatrix channelsextern uint8_t qt_burst_lengths[QT_NUM_CHANNELS];tag_sensor_tStructureInput / OutputUsetag_sensor_tOutput from the libraryData structure which holds the internal sensor state variables used by thelibrary.Fields Type CommentState uint8_t internal sensor stategeneral_counter uint8_t general purpose counter: used for calibration, drifting, etcndil_counter uint8_t drift Integration counterThreshold uint8_t sensor detection threshold. Refer to section 5.4.1 Detect threshold for moredetailstype_aks_pos_hyst uint8_t holds information for sensor type, AKS group, positive recalibration flag, andhysteresis valueBit fields UseB1 : B0Hysteresis. Refer to section 5.4.2 Hysteresis for moredetailsB2positive recalibration flagB5:B3AKS group. Refer to section 5.4.5 for more detailsB7:B6sensor typefrom_channel uint8_t starting channel number for sensorto_channel uint8_t ending channel number for sensorIndex uint8_t index for array of rotor/slider valuesqt_lib_siginfo_tStructureInput / OutputUseqt_lib_siginfo_tOutput from the libraryData structure which holds the information about the library variant and itsversion information.qt_lib_siginfo_t structure definition for a QTouch acquisition method library variantFields Type Commentlibrary_version uint16_t Holds the library version information.Bit fieldsUseB3 : B0Patch version of the libraryB7 : B4Minor version of the libraryB15:B8Major version of the librarylib_sig_lword uint16_t Holds the general information about the libraryBit fieldsUseB1 : B0 Library Type :00 : QTouch acquisition method01 : QMatrix acquisition methodB2Compiler tool chain used288207K-AT42-09/11