QTouch® and mTouch® Solution Terminology

Last modified by Microchip on 2023/11/09 08:55

This table is based on QTouch^® library v5.0 and mTouch^® library v2.5.

Parameter Categories	Parameter Description	Parameter Name in QTouch	Configurable in Atmel START	Parameter Name in mTouch	Configurable in MCC	Additional Details
Touch Basic Terms	Sensor acquisition value	Signal	No	Reading	No
	Reference value used for touch detection	Reference	No	Baseline	No
	Difference between acquisition and reference	Delta	No	Deviation	No
	State of touch detection	Detect	No	Pressed	No
	Measurement technique	Dual-slope measurement	No	Differential CVD	No
Sensor Definitions	Key sensor which reports ON/OFF status	Button	Yes	Button	Yes
	Linear touch sensor	Slider	Yes	Slider	Yes
	Angular touch sensor	Wheel	Yes	Wheel	Yes
	Proximity sensor	Button with high gain	Yes	Proximity	Yes	Proximity could be created by configuring a button with high gain and driven shield in QTouch. No specific configuration settings are available.
Sensor Technology	Self-capacitance sensor	Selfcap	Yes	sensor	Yes	Requires one Y-line sense pin per button.
	Mutual capacitance sensor	Mutualcap	Yes	Not Available	No	Requires one X-line drive pin and one Y-line sense pin per button.
Sensor Acquisition Parameters	Touch measurement periodicity	Scan rate	Yes	Scan Rate	Yes	MCC mTouch configurator has options to control the scan rate using TMR1 and scan the sensor in free running mode.
	Touch measurement frequency	Acquisition frequency	Yes	Not Available	No
	Sensor acquisition interrupt priority	PTC interrupt priority	Yes	Not Available	No	PTC interrupt priority only applicable on SAM devices.
Button Configuration Parameters	Sensor's detect threshold	Sensor detect threshold	Yes	Threshold	Yes
	Sensor's out-of-detect threshold	Sensor detect hysteresis	Yes	Sensor detect hysteresis	Yes
	Group selection for adjacent key suppression	AKS group	Yes	AKS group	Yes	AKS can be used when touching multiple sensors is not allowed in a system.
	Method selection for button status update	Not Available	No	Interface method	Yes	Callback or polling needs to be used to notify/update the application.
Slider/Wheel Configuration Parameters	No. of segments in a slider/wheel	No. of buttons	Yes	No. of Segments	Yes
	No. of unique positions reported by the slider/wheel	Resolution	Yes	Resolution	Yes
	Inactive area on both ends of the slider	Dead band Percentage	Yes	Dead band Percentage	Yes
	No. of positions you have to move before the touch position is reported	Position hysterisis	Yes	Position hysterisis	Yes
	Slider/wheel detect threshold	Threshold	Yes	Threshold	Yes
Proximity Configuration Parameters	Gain for deviation integration filter	Not Applicable	No	Deviation integration filter: gain	Yes
	Enable median filter	Not Applicable	No	Median filter	Yes
	Window for median filter	Not Applicable	No	Median filter: window	Yes
Sensor Node Parameters	Pin selection	Y-line, X-line	Yes	Pin	Yes	Mutual capacitance sensor requires one X-line drive pin and one Y-line sense pin per button.
	Acquisition clock prescaler	Prescaler for PTC	Yes	Not Available	No	MCC mTouch configurator will calculate the prescaler for ADC based on Fosc automatically.
	Internal series resistor selection	Series resistor	Yes	Not Available	No
	Gain setting for touch signal/reading	Digital/analog gain	Yes	Not Available	No
	IIR filter for touch signal/reading	Not Available	No	Reading filtering: level	No	In mTouch, new reading is updated as ((oldreading-(oldreading»filter level))+(rawsample»filter level)).
	Gain setting for touch reference/baseline	Not Available	Yes	Baseline filtering: gain	Yes	In mTouch, new baseline is updated as ((oldbaseline-(oldbaseline»gain))+reading).
	Scaling for deviation	Not Available	No	Deviation scaling	Yes	In mTouch, the deviation value is calculated as ((reading - baseline)»scaling).
	Number of samples taken for each measurement	Filter level	Yes	Oversample	Yes
	Sensor charging time	Charge share delay (CSD)	Yes	Precharge time	Yes	CSD indicates the number of additional cycles that are inserted within a touch measurement cycle. Precharge time is the amount of time spent charging the internal and external capacitors.
	Settling time delay	Not Applicable	No	Acquisition time	Yes	Acquisition time is the amount of time spent allowing the capacitors to equalize to a median voltage after being precharged to opposite states.
	Additional internal capacitance to the sensor nodes	Not Available	No	Additional sample capacitance	Yes	This is used to improve the match between internal and external capacitance for a better sensing performance.
Sensor Configuration Parameters	Enable auto-calibration	Sensor charge time auto-tune	Yes	Auto-calibration	Yes	For AVR devices, enabling this setting will automatically set the number of additional charge cycles needed to ensure full charging of the touch sensor. For SAM devices, enabling this setting will automatically set the pre-scaler setting needed to ensure full charging of the touch sensor. For PIC devices with HCVD, enabling this setting will automatically set acquisition time and additional internal capacitor. When the option is disabled, you need to manually set these parameters and ensure full charge transfer of the touch sensor.
	Enable noise performance improvement and water tolerance	Enable driven shield	Yes	Driven shield	Yes	Both QTouch and mTouch can assign a dedicated driven shield pin. Having a dedicated shield improves both noise performance and water tolerance. PTC devices, PIC16LF156x and ADCC devices can drive non-scanning sensors as the shield, which improves water tolerance.
Sensor Touch Parameters	No. of additional touch measurements to confirm touch	Detect integration (DI)	Yes	Debounce	Yes
	No. of additional touch measurements to confirm an out-of-touch detection	Away from touch detect integration	Yes	Debounce	Yes
	Threshold for out-of-touch recalibration	Away from touch recalibration threshold	Yes	Negative threshold	No	Negative threshold is configurable in mTouch code and not in MCC.
	No. of additional touch measurements to confirm out-of-touch recalibration	Not Available	No	Consecutive decodes	Yes
	Rate of change of reference (baseline) for positive delta (deviation)	Towards touch drift rate	Yes	Baseline filtering: update	Yes	For QTouch, value is scaled by 200 ms. In mTouch, a baseline update is done after this number of sensing cycles.
	Rate of change of reference (baseline) for negative delta (deviation)	Away from touch drift rate	Yes	Baseline filtering: update	Yes	Common value for towards touch and away from touch in mTouch. For QTouch, the value is scaled by 200 ms.
	Amount of time the change of reference needs to be paused after removing the finger	Drift hold time	Yes	Baseline Hold	No	Value is scaled by 200 ms for QTouch. This is configurable in the firmware for mTouch.
	Re-bursting mode	Re-burst mode	Yes	Re-burst mode	Yes
	Enable sensor ON timeout	Max-ON duration (MOD)	Yes	Press timeout	Yes	Set the value of MOD as zero in Atmel START to disable sensor ON timeout in QTouch.
	Sensor ON timeout unit	Not Available	No	Press timeout unit	Yes	In QTouch, unit is time in ms. In mTouch, the unit is main loop task calls by default.
	Set maximum sensor ON time/counts	Max-ON duration (MOD)	Yes	Press timeout counts	Yes	In QTouch, value is scaled by 200 ms.
Frequency Hop Parameters	Enable multiple burst frequencies	Enable frequency hop	Yes	Enable AFA	Yes	Frequency hopping is enabled by default in mTouch.
	Enable auto changing of burst frequency	Enable frequency auto tuning	Yes	Automatic frequency adaptation	Yes	Intelligently choose scan frequency at run-time to avoid noise frequency and its harmonics.
	Timer selection for frequency hop	Not Available	No	AFA filter timer	Yes	The PIC with ADCC doesn't need a timer to implement the frequency hopping.
	Number of frequencies used in touch measurement	Frequency steps	Yes	Max/Min Frequency	No	The mTouch will pick the frequencies in a range, which is configurable in the firmware.
	Threshold for noise frequency replacement	Maximum variance	Yes	Noise Threshold	No	This can be configured in the firmware for mTouch.
	Count for noise frequency replacement	Tune in count	Yes	Over Limit Threshold	No	This can be configured in the firmware for mTouch.
Clock Configuration Settings	Oscillator selection	Oscillators	Yes	Oscillator select	Yes	Select the oscillator from the list.
	External clock selection	Oscillators	No	External clock select	Yes	Select the external clock source from the list if an external oscillator is selected.
	Internal clock frequency selection	Clock settings: prescaler	Yes	HF internal clock	Yes	Set the internal clock frequency by selecting the prescaler value.
	External clock frequency selection	Frequency	Yes	External clock	Yes	Enter the external clock frequency if an external oscillator is selected.
	Clock source prescaler	Generic clock generator division	Yes	Clock divider	Yes	The internal/external clock selected is divided by this prescaler.
	Enable low voltage programming	Not Available	No	Low voltage programming enable	Yes
	CPU and peripheral clock selection	Clock source	Yes	Not Available	No	Select the clock generator source for CPU and components from the list in QTouch.
	CPU clock divider	CPU clock prescaler	Yes	Not Available	No	The CPU frequency will be the generic clock selected for the CPU divided by the prescaler.
	Enable watchdog timer	Not Available	No	Watchdog timer enable	Yes

QTouch® and mTouch® Solution Terminology

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