Touch sensing controller (TSC) RM0351
788/1830 DocID024597 Rev 5
26 Touch sensing controller (TSC)
26.1 Introduction
The touch sensing controller provides a simple solution for adding capacitive sensing
functionality to any application. Capacitive sensing technology is able to detect finger
presence near an electrode which is protected from direct touch by a dielectric (for example
glass, plastic). The capacitive variation introduced by the finger (or any conductive object) is
measured using a proven implementation based on a surface charge transfer acquisition
principle.
The touch sensing controller is fully supported by the STMTouch touch sensing firmware
library which is free to use and allows touch sensing functionality to be implemented reliably
in the end application.
26.2 TSC main features
The touch sensing controller has the following main features:
• Proven and robust surface charge transfer acquisition principle
• Supports up to 24 capacitive sensing channels
• Up to 8 capacitive sensing channels can be acquired in parallel offering a very good
response time
• Spread spectrum feature to improve system robustness in noisy environments
• full hardware management of the charge transfer acquisition sequence
• Programmable charge transfer frequency
• Programmable sampling capacitor I/O pin
• Programmable channel I/O pin
• Programmable max count value to avoid long acquisition when a channel is faulty
• Dedicated end of acquisition and max count error flags with interrupt capability
• One sampling capacitor for up to 3 capacitive sensing channels to reduce the system
components
• Compatible with proximity, touchkey, linear and rotary touch sensor implementation
• Designed to operate with STMTouch touch sensing firmware library
Note: The number of capacitive sensing channels is dependent on the size of the packages and
subject to IO availability.
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