Design Automation


Open-source touch sensing library

1 April 2009 Design Automation

To help engineers implement touch-sensitive controls with minimum additional effort, cost and size, STMicroelectronics has made available an open-source capacitive touch sensing software library for its 8-bit STM8 MCU platform.

The software library transforms any 8-bit STM8 MCU into a capacitive touch-key controller. Designers can combine touch sensing functions through multiple configurations, such as touch keys, wheels or sliders, while preserving the traditional STM8 MCU features for the application firmware, including communication, LED control, beeper and LCD control. The software is provided as royalty-free C source code and offers engineers the flexibility to configure, adapt or accommodate the library according to application needs.

Human touch is detected by monitoring the charge and the discharge timing cycle of an RC network formed by a single resistor and the touch electrode capacitance. Depending on which STM8 variant is used, as many as 24 individual touch pads can be supported. The touch sensing library only uses a small amount of the chip’s memory and processing capability, allowing designers to combine other application tasks in a single device. To optimise power consumption, the software also takes advantage of the STM8’s low-power modes.

The touch sensing library embeds advanced tools to help define keys, slider controls or rotary sensors, and to optimise touch sensitivity by adjusting parameters such as the touch detection threshold and the resolution of sliders or rotary controls. There are also innovative programmable features to optimise measurement accuracy and make the final application immune to noise.

An embedded automatic calibration software layer saves final adjustment during manufacturing and enables faster time to market. To maximise long-term reliability the library contains an environmental change system (ECS), which compensates for natural fluctuations in operating voltage and capacitance, as well as environmental effects such as temperature and humidity.

As well as source code for the touch-sensing software library, full supporting documentation includes the API description, a user manual for the software library, application notes and board layout recommendations, as well as code examples.



Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Analysis of switch-mode power supply: inductor violations
Altron Arrow Editor's Choice Power Electronics / Power Management
Common switch-mode power supply (SMPS) design errors are discussed, and their appropriate rectification is specified, with details on complications that arise with the power stage design of DC-DC switching regulators.

Read more...
Microsoft Windows IoT on ARM
Altron Arrow Computer/Embedded Technology
This expansion means that the Windows IoT ecosystem can now harness the power of ARM processors, known for their energy efficiency and versatility.

Read more...
Accelerating the commercialisation of the 5G IoT markets
Altron Arrow Editor's Choice Telecoms, Datacoms, Wireless, IoT
Fibocom unveils Non-Terrestrial Networks (NTN) module MA510-GL, enabling satellite and cellular connectivity to IoT applications.

Read more...
Microchip introduces ECC608 TrustMANAGER
Altron Arrow Circuit & System Protection
To increase security on IoT products and facilitate easier setup and management, Microchip Technology has added the ECC608 TrustMANAGER with Kudelski IoT keySTREAM, Software as a Service (SaaS) to its Trust Platform portfolio of devices, services and tools.

Read more...
xG26 sets new standard in multiprotocol wireless device performance
Altron Arrow AI & ML
Silicon Labs has announced its new xG26 family of Wireless SoCs and MCUs, which consists of the multiprotocol MG26 SoC, the Bluetooth LE BG26 SoC, and the PG26 MCU.

Read more...
SolidRun unveils new SoM
Altron Arrow AI & ML
SolidRun and Hailo has unveiled a game-changer for engineers and AI product developers with the launch of their market-ready SoM, which packs the cutting-edge capabilities of the Hailo-15H SoC.

Read more...
An evolutionary step in customisable logic
Altron Arrow DSP, Micros & Memory
Microchip Technology is offering a tailored hardware solution with the launch of its PIC16F13145 family of microcontrollers, which are outfitted with a new Configurable Logic Block module.

Read more...
MCU for battery-powered applications
Altron Arrow DSP, Micros & Memory
Included in ST’s family of devices is the STM32U031, an ultra-low-power MCU featuring an ARM Cortex-M0+ 32-bit core running at up to 56 MHz.

Read more...
LoRaWAN-certified sub-GHz module
Altron Arrow Telecoms, Datacoms, Wireless, IoT
The STM32WL5M from ST Microelectronics is the company’s first LoRaWAN-certified module which incorporates two cores, one of them being a wireless stack to optimise the creation of sub-GHz applications.

Read more...
Dual-port USB-C power delivery solution
Altron Arrow Power Electronics / Power Management
Infineon’s CYPD7272-68LQXQ is the tray packing option of the company’s dual-port USB-C power delivery solution and features an integrated dual-port USB-C PD + DC-DC controller.

Read more...