Volume 119 No. 15 2018, 793-798 ISSN: 1314-3395 (on-line version) url: http://www.acadpubl.eu/hub/ http://www.acadpubl.eu/hub/ DESIGN AND IMPLEMENTATION OF MOBILE WIRELESS OSCILLOSCOPE AND FUNCTION GENERATOR Deepak P [1], Nisanth V [2], Paris Rahman S [3], Lakshmi S [4] [1][2][3]B.E IV year, [4] Assistant professor Department of Electronics and Communication Engineering VEL TECH MULTI TECH DR.RANGARAJAN DR.SAKUNTHALA ENGINEERING COLLEGE Abstract: Smart phones have enough processing power to evaluate data and to analyze it. Smart phones have different wireless communication options like Bluetooth. Nowadays many people started using smartphone for controlling and monitoring purpose, because smartphone uses powerful processor like personal computer. The Smartphone operates on Android-Based OS or Window OS. They have large display or powerful processor to display and check the measured data on their screen. The major advantage of the smartphones is the wireless connectivity is based on its ability so that they could be used in measurements for displaying the results display the results students can do laboratory experiment instantly at home or at workplace their by replacing large size, high cost and non-portable oscilloscope and function generator into hand-held device which do functions of dual Scope oscilloscope and function generator with help of Arduino Uno and a Smartphone to display the results. Keywords: Smartphone, Arduino Uno, ATMEGA328 Kit and HC-05 Bluetooth Module. 1. INTRODUCTION There are different instruments used in oscillators, signal generators and multi users.the application of these instruments are used in schools, colleges and research labs. These instruments have disadvantages in form of their bulky size and high cost. These devices have good enough screen sizes to display results. Smart phones have enough processing power to evaluate data and to analyze it. Smart phones have different wireless communication options like Bluetooth, Wi-Fi and NFC. The open source Android OS is used different smart phones is mainly used to develop this application on a single device. To generate the frequency and waveforms are selected within the mobile application and an exact waveform with fixed frequency can be done by utilizing DAC. 2. HARDWARE DESIGN The instrument setup is shown in the fig 1. There are signal Conditioner circuit and current sensing circuit for the oscilloscope and function generator. The core of the instrument is an Arduino Uno ATMEGA328 Microcontroller which does the general purpose tasks such as ADC, DAC, UART interface and so on. Arduino processors are the best choice in the market, because it is inexpensive, has low power modes and I/O channels. Arduino Uno ATMEGA328 is is easy to program has enough I/O port to serve 1 793
the connected devices. The communication between the device and the Smartphone is obtained by Bluetooth connectivity. The function generator is generating the frequency between the range of 10 Hz to 150 Khz has high accurate and low noise sine, square and triangular waveform within the frequency range of 10 Hz to 150 khz. The signal generator circuit is built on DAC-0808.The DAC-0808 is 8 bit parallel DA converter and a signal conditioner circuit. The DAC is interfaced with Arduino Microcontroller by internal USART. The external DAC is used, because Arduino cannot perform DAC operation standalone. FIG.1 Structure of Mobile Wireless Oscilloscope and Dual Oscilloscope. 3 IMPLEMENTATION OF THE OSCILLOSCOPE The Smartphone oscilloscope is implemented with signal conditioning circuit LM358 and internal ADC of the Micro-Controller. The signal conditioning circuit is used to handle negative voltage input. The peak to peak voltage is measure by internal ADC. The supply voltage attenuate the amplitude to the ADC input range. AC voltage is measured is also necessary to add an offset voltage to the input signal to get a mid-supply virtual ground. LM358 is suitable for the input circuit because as has low noise, high speed and the output can be driven all the way to the supply. 4. IMPLEMENTATION OF THE FUNCTION GENERATOR FIG.3 Mobile Function Generator Interface 5. ANDROID APPLICATION 2 794
The mobile application is developed by MIT App Inventor software. The software can be connected to the hardware setup via Bluetooth for implementation either the function generator or the oscilloscope. The communication is based on a serial communication, where 1 byte data packets are transferred via Bluetooth. The function generator visuals are shown in fig 4. of the screen. FIG.4.1 Mobile Oscilloscope Output of ~50Hz FIG 4. View of the generator output using Android Systems In this function generator user interface a particular waveform is selected by entering particular frequency value in Hz and pressing send button, the particular waveform with same frequency is obtained at DAC output terminal. The dual scope oscilloscope is implemented in android user interface which measures Vp-p, Vmax, Vmin, frequency and these functions appear on the corner FIG.4.2 Mobile Oscilloscope Output ~50Hz Square Wave 3 795
software s on smartphones to communicate and collect data from the real-time applications. 7.SUMMARY FIG 4.3 Mobile Oscilloscope Output of ~50Hz triangular wave 6. BENEFITS OF THE INSTRUMENT This instrument is inexpensive and can be used in bachelor and master degree program for students to perform their lab at their home and it is easy to perform experiments in university labs. It replaces the huge and expensive lab instruments. The students can understand basic electronics and physical laws easily by using this tool. They can use the oscilloscope function for finding amplitude and frequency of output waveform. In embedded systems class the students can look inside the box and follow along the principle of complex measurement system. Customized software such as C,checks the instrument functions. In programming class students can write Android based portable oscilloscope and function generator smart phone replaces the bulky instruments. The system is portable, cost efficient, safe and no need of manual adjustment. To conclude a cost-effective Mobile Wireless Oscilloscope and Function Generator was designed, implemented and tested. The instrument has many advantages like mobility, safety, accuracy and needs only a Smartphone with Bluetooth capability which is very common now days. The benefits of the scope generator is that there is no need to install any additional software derivers on modern computer platforms. Simplicity of this work it makes the device very cost effective to use for learning purposes. It is easy to modify the software. The instrument with logic analyzer and batterypowered version to make a more portable version of the instrument. ACKNOWLEDGEMENT The authors gratefully acknowledge the contribution of Govt. of India for Financial Assistance, DST-FIST F.NO:SR/FST/College-189/2013 8. REFERENCE [1] Andres Udal and Martin Jaanus,Department of Computer Control, Tallinn University of Technology. USB Audio Chip Based Oscilloscope and Signal Generator for Mobile Laboratories. ICSES 2012 4 796
[2]Dénes Fodorand Robert Katona Texas Institution MSP430 Microcontroller Based PortableMulti- Purpose Instrument for Android Platforms. European Embedded Design in Education and Research Conference (EDERC 2014) Milan, Italy [3]Dipesh Kumar Pokar, Mithila Jaybhye,, Priyanka K. Katkar, Prof. Trikolikar A.A Wireless oscilloscope using Zigbee International Journal of Advanced Research in Computer Engineering & Technology.March 2015. [4] Preethi.E, A.Mohammed Abbas, Prabhu Kumar, P.G.Kuppusamy, Bio medical signal processing using memristor emulator CT FIR filter Int journal of control theory and applications, PP 3589-3597, VOL 9(9), 2016. [5] Kalyani Ganvir and Hemant Waghmare, Oscilloscope on Android Phone, Volume 3, Issue 4, ISSN:2277 128X, 2013. [6] E Dhiravidachelvi, V Rajamani, PA Janakiraman, Speedy Location of Optic Disc in Retinal Images Journal of Medical Imaging and Health Informatics 6 (8), 1906-1912, 2016 5 797
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