3.2.5
Presence, Hold and Approach
The MGC3140 detects the presence of a hand when the following conditions are met:
1.
Whenever the SD of any single electrode exceeds the Presence Threshold Single Electrode
Threshold parameter.
2.
Whenever the SD of all Rx electrodes exceed the Presence Threshold All Electrodes Threshold
parameter.
Once the MGC3140 has detected the presence of a hand, it does the following:
1.
Sets a Hand Presence flag. This flag can be seen in the Presence Hold State window.
2.
Starts a timer for Hand Present gesture event.
When the hand-present timer reaches the Presence Duration time, the presence is reported, and a Hand
Present is indicated in the Gestures window.
Figure 3-6. Hand Present Symbol
When the hand-hold timer reaches the hand-hold duration time, the Hand Hold is reported and a Hand
Present is indicated in the Gestures window.
Figure 3-7. Hand Hold Symbol
The Hand Hold flag remains set unless the hand moves. The amount of movement allowed in order to
keep the Hand Hold flag set is controlled by the Hand Tremble Threshold. This parameter specifies the
amount of movement that a hand can move and still be classified as holding.
•
Low values – only a small movement is necessary to clear the Hand Hold flag.
•
High values – the hand can move and the Hand Hold flag will stay high.
If the amount of movement is sufficient to clear the Hand Hold flag, then:
1.
The hand-hold timer is restarted, providing the hand is still present.
2.
Any hand-hold indication in the Gesture window is cleared.
3.
The ending of the Hand Hold is reported.
The Default Presence and Hold Default parameters are generally acceptable to most users, although the
Hold Tremble Threshold may require some tuning.
The ActiveOutside parameter chooses if Hand Hold flag and Presence gesture can be active when the
user is outside the sensor, but still in sensing space.
•
ActiveOutside
checked
(default) means that Hand Presence is required to set Hand Hold and that
Presence Duration starts counting on the rising edge of the Hand Presence Status flag.
•
ActiveOutside
unchecked
means that Hand Inside is required to set Hand Hold and that Presence
Duration starts counting on the rising edge of the Hand Inside Status flag.
The use of the Active Outside flag requires accurate knowledge of the sensor dimensions and accurate
position reporting.
Related Links
MGC3140
Tuning
©
2018 Microchip Technology Inc.
User Guide
DS40002055A-page 13
