An extension of the button is a proximity sensor. A single sensor node is
monitored for a change in capacitance exceeding a pre-configured threshold. In the same
way as the button, the sensor is considered to be ‘In Detect’ when that threshold
is exceeded. Once in detect, a relative measurement of the contact distance is made by
scaling the touch delta between two thresholds - the initial ‘Detect’ threshold
and a second ‘Full Contact’ threshold.
Note: As the proximity sensor relies on the
capacitive load of a distant object, the ‘apparent distance’ to the contact will
depend on the shape and size of the contact.
I.e., an open hand in proximity at 10 cm will ‘appear’ closer than an
extended finger at 10 cm, as it has a larger influence on capacitance due to a larger
surface area at the same distance.
Capacitance (C) is proportional to Area (A) and inversely proportional to
distance (d). Also, the grounding has a significant impact on sensitivity, and so does
the range.
The online versions of the documents are provided as a courtesy. Verify all content and data in the device’s PDF documentation found on the device product page.
