This paper demonstrates a support vector machine (SVM) based capacitive touch screen scheme that can discriminate stylus and finger at the same time. The tip of a stylus provides pulses at the higher frequency than the transmitting (Tx) pulse of a touch screen. Then the digital value acquired from an analog-to-digital converter is transferred to an SVM classifier to make the decision of which touch is applied among no-touch, finger-touch, and stylus-touch. Three types of touches are processed on the SVM algorithm. The proposed method is evaluated by means of an 8 inch capacitive touch panel, connector board, Tx/Rx driver board, and host processor board. While Tx pulses are applied at 5 V and 32 kHz that lead to the 200 Hz reporting rate, stylus pulses are produced at 3 V and 315 kHz. The resultant bit error rate is measured as less than 10−6 for all types of touches.

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Visible light identification (VLID) is a user identification system for a door lock application using smartphone that adopts visible light communication (VLC) technology with the objective of high security, small form factor, and cost effectiveness. The user is verified by the identification application program of a smartphone via fingerprint recognition or password entry. If the authentication succeeds, the corresponding encoded visible light signals are transmitted by a light emitting diode (LED) camera flash. Then, only a small size and low cost photodiode as an outdoor interface converts the light signal to the digital data along with a comparator, and runs the authentication process, and releases the lock. VLID can utilize powerful state-of-the-art hardware and software of smartphones. Furthermore, the door lock system is allowed to be easily upgraded with advanced technologies without its modification and replacement. It can be upgraded by just update the software of smartphone application or replacing the smartphone with the latest one. Additionally, wireless connection between a smartphone and a smart home hub is established automatically via Bluetooth for updating the password and controlling the home devices. In this paper, we demonstrate a prototype VLID door lock system that is built up with LEGO blocks, a photodiode, a comparator circuit, Bluetooth module, and FPGA board.