The STMTouch capacitive touch-sensing firmware library has been extended to enable designers to add user-interface features to applications using 8-bit STM8 microcontrollers.
The second-generation of STMicroelectronics STMTouch firmware now supports over 200 STM8 part numbers, including the STM8S and the STM8L families.
Support has also been added for touch detection via charge-transfer, which delivers high sensitivity and robustness. Simultaneous channel acquisition has been added to reduce 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.
To complement the enhanced second-generation firmware, an evaluation board has been added to the STMTouch development platform which supports 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 a 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.
The STM8 touch sensing firmware library provides:
- 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.
The STMTouch touch-sensing library for STM8 microcontrollers can be downloaded free of charge from www.st.com. The STMT/8L-EV1 evaluation board for touch development on STM8L microcontrollers is priced at $49. The STM8/128-EV/TS supporting the STM8S family is available for $179.