Touch-sensing firmware library extended, enhanced for microcontrollers

Second-generation STMTouch capacitive sensing firmware library extended and enhanced to increase performance and add support for new STM8 microcontroller families.


STMicroelectronics has extended and enhanced its STMTouch capacitive touch-sensing firmware library, allowing designers to add advanced user-interface features to applications using 8-bit STM8 microcontrollers.

The second-generation STMTouch firmware now supports over 200 STM8 part numbers, including the advanced STM8S family and the STM8L, featuring ultra low-power EnergyLite technology. Another new feature is support for touch detection via charge-transfer, which delivers high sensitivity and robustness. In addition, simultaneous channel acquisition reduces CPU usage to help designers optimize application features and power consumption. The library also provides improved wheel and slider controls that feature 256-level resolution while using only three microcontroller I/Os as sensor channels.

Touch controls implemented using the STMTouch firmware library occupy a low memory footprint and require minimal use of STM8 peripherals, allowing developers to consolidate user-interface and application tasks in a single device.

“Customers have already achieved some notable product and commercial successes using our first-generation firmware, including Bluetooth headset, PC and printer products,” said Jean-Philippe Dumas, Product Line Marketing Manager, Microcontroller Division, STMicroelectronics. “Our latest enhancements to the STM8 touch sensing firmware library will improve performance and drive further integration of touch-enabled user interfaces in products such as kitchen appliances, mobile devices, multimedia products and professional equipment.”

To complement the enhanced second-generation firmware, the STMTouch development platform adds a new evaluation board supporting the ultra-low-power STM8L family and also features STM Studio software enabling developers to tune touch-sensing parameters. STM Studio is a PC-based tool offering an easy-to-use GUI that provides visual indication of sensor responses. The development platform also features an STM8S evaluation board, as well as the API description, application notes, code examples, and layout recommendations for production boards. C-compiler support has also been expanded, as the latest release is compatible with Cosmic, IAR and Raisonance compilers.

 Major features of the STM8 touch sensing firmware library:

  • Complete library with acquisition, post processing and API layers
  • C source code provided
  • Up to 24 keys and two wheels/sliders supported
  • Support for both charge-transfer and RC-timing touch detection
  • Enhanced processing features for optimized sensitivity and immunity
  • Active shield feature
  • Automatic calibration software
  • Built-in compensation of environmental fluctuations


- Edited by Amanda McLeman, Control Engineering,

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