As smartphones brought about the trend of touch control, the need for different sizes of touch panels have gradually become popular in people’s lives replacing traditional physical buttons; for example, POS machines, Kiosk machines in convenience stores, electronic whiteboards and signage in department stores. It also brought about the development and progression of related technologies.
For a complete touch display system, not only is there the most front-end touch panel, it usually needs a microcontroller to read the raw data of the front-end touch sensor, and then provide the processed signal to the host computer (responsible for the control and output of the human machine interface screen), and complete the switching of screens. The performance of the microcontroller has great impacts on the smoothness of overall touch system operations.
Touch system reference architecture diagram is as shown below:
Nuvoton NuMicro M480 series is based on the Arm Cortex-M4F core; its basic frequency can reach up to 192 MHz, able to quickly run users’ touch algorithm. It also includes a floating point unit (FPU) and digital signal processing instructions (DSP), effectively improving the execution efficiency of the digital filter; it also provides multiple sets of SPI interfaces that can reach a maximum of 96 MHz that can be used to connect front-end touch sensors. 2-bit mode is also provided so that reading and writing can be performed to two sets of touch sensors simultaneously within a frequency time; it also includes the PDMA interface so that the precision and accuracy of the touch control can be improved without having to exchange capacitance change data with the front touch sensor through the CPU.
Through the 2-bit mode of the QSPI interface of Nuvoton NuMicro M480 series, data can be acquired from two different front-end touch sensors at the same time, reducing the problem of unsynchronized sensing data due to transmission delays; and by running touch algorithms with the high-speed CPU, built-in floating point unit and digital signal processing instructions (DSP) of Nuvoton’s NuMicro M480 series, high-performance touch panel controls can be achieved.