Fujitsu Adds High-performance Capacitive Touch Functionality to Its FM3 Family of ARM Cortex-M3 Based Microcontrollers

The new technology, developed by FSEU in Europe, combines high sensitivity with low system load, and supports developers in creating flexible and tailored HMI solutions.

FM3 ‘Right-Sized’ Solutions
Since they first launched at the end of 2010, Fujitsu’s FM3 family has developed into an array of more than 300 compelling microcontroller products. With advanced peripherals, including flexible timers to control various types of inverters, serial communication interfaces ranging from a simple UART, over CAN, USB and up to dual-channel Ethernet, high-performance Flash memory and many more, the FM3 family addresses a wide range of industrial, home appliance and medical applications.

Many such applications require a Human-Machine-Interface, and increasingly require rich functionality as well as aesthetic design. Capacitive touch control has become one of the most popular technologies to fulfill the requirements of modern HMI implementations. The FM3touch capacitive touch library allows easy integration of capacitive touch functionalities such as buttons, sliders, scroll wheels and even touch pads, with a minimum of additional hardware and software effort.

Maximum flexibility
Fujitsu’s FM3touch takes full advantage of an advanced 12-bit ADC, present in all FM3 devices, enabling high-speed acquisition, high sensitivity and low system load. Since all FM3 devices offer two or even three independent ADC units, maximum flexibility and resource availability is achieved, fulfilling all application requirements. Configurable environmental drift calibration assures stable operation, and a flexible sensor grouping allows numerous layout options for sliders, buttons, scroll wheels and touch pads. In addition to a simple on / off status, the touch signal strength of each sensor can be read out, and special notification functions can be triggered upon events such as button press / release and position change of a slider, among others.

FM3touch uses an ADC-based, patent-pending capacitive sensing algorithm to reach a high sensitivity of only a few femto-Farad, using one pin-per-touch input channel without the need for external components. Together with the wide variety of available FM3 products from 48 up to 176 pins, different Flash sizes and combinations of advanced peripherals, the right-sized device can be chosen for every application.

Easy deployment
A graphical PC tool can be used to monitor the touch data and to facilitate the setup of different parameters. It can be easily connected to the target system by a serial connection, so that parameter fine-tuning can be performed directly at the end application.