STM8T143 STMicroelectronics, STM8T143 Datasheet - Page 19

• Manufacturer Part Number: STM8T143
• Description: Single-channel capacitive sensor for touch and proximity detection
• Manufacturer: STMicroelectronics

STM8T143
5.4
Dynamic calibration (DYCAL)
The STM8T143 DYCAL process is based on a dynamic threshold and reference
management which allows tracking of slow environmental changes even when the sensor is
in touch state. A low threshold is used to detect the proximity of an object, with a higher
threshold for touch detection. DYCAL is performed when a touch condition is detected for
longer than a certain period (t
operation is performed instantanéously .
touch event (DYCAL_T) and for the release event (DYCAL_R).
After the DYCAL_R event, the AET process is frozen for a t
Figure 9.
1. t
2. The release threshold (RTh) is a ratio of the the touch threshold (TTh). TTh is selected by the “touch
3. T
4. In touch condition, the ECS allows the reference to adapt a slow signal variation change.
detection threshold” option bits (TTh). The ratio is selected by the “release threshold ratio” option bits.
Figure 12: IIR filter formula
AET_HALT
F
Th = Touch freeze threshold. Please refer to
= AET HALT period after end of detection.
DYCAL general operation
for the T
DYCAL_T
Doc ID 18315 Rev 3
F
Th description.
). When a release condition occurs, the DYCAL
Figure 9
Table 17: General capacitive sensing characteristics
represents the DYCAL operation for the
AET_HALT
STM8T143 processing
delay.
and
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