STM8T143 STMicroelectronics, STM8T143 Datasheet - Page 22

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

STM8T143 processing
5.5
5.5.1
Note:
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Environment control system (ECS)
ECS principle
The acquired signal value of the capacitive sensing channel increases or decreases
according to environmental conditions such as temperature, power supply, moisture, and
surrounding conductive objects. The STM8T143 includes a built-in digital infinite impulse
response (IIR) filter capable of tracking slow changes in the environment. It is called the
environment control system (ECS). This is a low pass filter with a gain of one. The filter
makes the reference follow slow changes of the signal while fast changes are recognized as
a touch or proximity.
Figure 12. IIR filter formula
If a touch or proximity is detected, the ECS is disabled for the duration of the reference
freeze timeout. In this case, Y
detection ends, the filter is set as active again.
n
Doc ID 18315 Rev 3
= Y
n_1
. As soon as the reference freeze times out or the
STM8T143