Data Communication And Application Based On Smartphone Audio Interface

With the development of smartphone and mobile internet, intelligent hardware become increasingly popular in smart home, mobile medical, mobile payment, etc. And the communication way between mobile phone and peripheral equipment is important to intelligent hardware design. Now each smartphone has a uniform audio interface. The communication way based on the mobile phone audio interface will have a very good versatility and the advantages of low cost and convenience.This paper is in order to realize data communication through mobile phone audio interface. This paper designs to realize two audio coding modulation ways based on the characteristics of the audio interface channel. One is traditional FSK modulation, the other is a improved FSK modulation, and specific algorithm is designed for two kinds of modulation encoding process. The paper also designs audio interface communication protocol stack, including signal processing layer, link layer and the data frame format, and use the CRC checking algorithm to detect error and ARQ algorithm to ensure reliable data transmission.In addition, the paper designs the specific application hardware circuit, including communications processing circuit, compatible circuit to adapt two kind of audio interface standards, energy harvester circuit, and the intelligent power supply switching circuit based on the supplying of the battery, which is proposed in this paper.By the end of the paper shows a test and analysis of data communication for mobile audio interface design, presenting the test results of improved FSK coding and FSK coding of sending and receiving. In addition, it presents the bit error rate of the signal processing layer and analyzes transmission performance. Finally it shows a test for the energy harvester circuit by audio interface and analyzes the optimum power transmission conditions.