uSD: universal sensor data entry card

This paper presents an SD-based universal sensor data entry card, named uSD. The prefix "u" of uSD illustrates its most significant characteristic: universality, which means uSD is platform independent and compatible with heterogeneous platforms, truly plug-and-play. In this paper, we relate the design and implementation of uSD, especially about uSD\´s superiority over SDIO-based method. Additionally, SDK and programmer are provided for thirdparty to design further applications with uSD. Evaluations about performances of uSD are also developed, like power assumption, CPU and RAM usage. Our practical works including two demos well validate uSD\´s feasibility and its platform independence. uSD not only can help consumers with portable devices to access WSN conveniently and efficiently, but also are appropriate for researchers constructing testbed.