Table 3. Signal threshold usage documentation
Id Title Chapters
UM1913
Developing applications on STM32Cube with
STMTouch® touch sensing library
Debug with STMStudio
AN4316 Tuning a STMTouch-based application
Monitoring STMTouch driver variables using
STMStudio
Tuning of the Thresholds
Touchkeys thersholds
Linear and Rotary touch sensors thresholds
5.3 Charge transfer
The acquisition is based on the measurement of the sensor channel capacitance.
To ensure that the Cx capacitance is correctly charged, it is necessary to monitor the pin connected to the sensor.
On sensors and shield sides, it must observe a complete Charge/Discharge cycle.
Figure 7. Incomplete and complete charge transfert cycle
In this example , to complete the charge transfer cycles, the following parameter must be modified as below:
• INCREASE:
– htsc.Init.PulseGeneratorPrescaler
– htsc.Init.CTPulseHighLength
– htsc.Init.CTPulseLowLength
• DECREASE:
– Sysclk
Table 4. Charge transfer documentation gives a list of documents containing information about the charge
transfer.
Table 4. Charge transfer documentation
Id
Title Chapters
AN4299
Guidelines to improve conducted noise robustness on
STM32F0/F3/L0/L4 series touch sensing applications
Active shield
AN4316 Tuning a STMTouch-based application Charge transfer period tuning
AN5105
Charge transfer
AN5105 - Rev 1
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