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In this paper, a visible light communication transmitter using a LED matrix with low-cost LEDs is shown. This design use a DAC to control the LED drivers, through a discrete component current mirror circuit. The DAC is controlled using an FPGA, which together works as a highly configurable direct digital synthesiser. The design proposed in this paper is thus well suited as a transmitter node in a software defined radio using visible light communication. In this paper, we describe the design, and show its behaviour when programmed to transmit a number of carriers modulated with amplitude and phase modulation schemes.

This paper evaluates the opportunity to utilise external sensors through near field communication (NFC) for smartphones, both, in terms of energy consumption from the smartphones’ battery and time consumption of the smartphones’ user. Our developed sensor card enables external sensors to obtain information, for example, on the current temperature level, humidity level, UV level, and amount of ambient light. We demonstrate that our approach requires significantly less energy and time compared to alternatives which users of smartphones have. Furthermore, we analyse the impact of heat sources present in smartphones on the readings of temperature and humidity level sensors. We propose to externalise sensors in order to minimise the negative impact of temperature on sensors readings and, thereby, improving the accuracy of the measurements and the acquired sensor data.

People have become more aware about their environment and pay more attention to conditions, e.g., air quality, and UV light exposure. Conventional technologies for reading environmental conditions are expensive, bulky, situated, and do not meet people’s need for a mobile and portable tool for environmental fingerprinting on demand. We present a mobile-enabled client-server system for personalized environmental fingerprinting and crowdsourced environmental fingerprint datasets using a smartphone and a portable credit card-sized NFC powered sensor board.

In this paper, we present a new approach to interrogate sensors using Near Field Communication (NFC). This approach utilizes NFC data exchange format (NDEF) to report the sensor data directly to a cloud service through a smartphone. The new advantage in this approach is that no smartphone application is needed to move the data from the sensor to the cloud. We also discuss advantages and disadvantages of this approach compared to earlier NFC sensor interrogation solutions.

In this paper, we present and evaluate a new approach to communicate with inter-integrated circuit (I2C) enabled circuits such as sensors over near field communication (NFC). The NFC-to-I2C interface was designed using a non-standard NFC command to control the I2C bus directly from a smartphone, which was controlling both, the read and write operations on the I2C bus. The NFC-to-I2C interface was reporting back the data bytes on the bus to the smartphone when the transaction was completed successfully. The proposed system was tested experimentally, both, with write and read requests to a commercial microcontroller featuring a hardware I2C port, as well as reading a commercial I2C enabled humidity and temperature sensor. We present experimental results of the system which show that our approach enables an easy interface between smartphones and external sensors. Interfacing external sensors is useful and beneficial for smartphone users, especially, if certain types of sensors are not available on smartphones.

This paper describes a technique for calibrating the internal ambient light sensor (ALS) in smart phones. The calibration process depends on Near-Field Communication (NFC). The system consists of an NFC core implemented in an Field-Programmable Gate-Array (FPGA) development platform featuring the NFC analog front end circuit. In the proposed system, the smart phone interacts directly with a reference ALS through the NFC device The direct communication is possible with the help of a custom NFC command that controls an Inter-Integrated Circuit (I2C) master core in the FPGA. After the calibration process of the ALS in a smart phone is completed, the accuracy of the measurement is greatly improved. This is helpful to obtain precise information on the light intensity in indoor surroundings.