**4. Another approaches**

*LabVIEW - A Flexible Environment for Modeling and Daily Laboratory Use*

procedure diagram is shown in **Figure 14**.

*The filter applying to the body sound signal in the LabVIEW program.*

*The program with function of direct sound regenerating.*

LabVIEW data acquisition program based-on LIFA is shown in **Figure 13**, where the block of "Analog read pin" is located outside of the while loop to avoid the replication of the setup pin mode for each cycles. Here, the sampling frequency can directly input to the "control" block as 88 kHz to satisfy the requirement of whole spectrum range observation. For the compatibility, this experiment was check with all current LIFA package with LabVIEW 2018 sp1. The result suggested that the package of 1.3.0.26 is great deal for this development without any errors.

Because of the conversion from the acoustic wave to the electromagnetic wave, the signal is contaminated with electromagnetic wave noises, hence, the noises should be reduced to enhance the SNR for the observation. To ensure the noise minimization, the digital band-pass filter is applied with cut-off frequencies are set at 5 Hz for low frequency cut and 35 kHz for high frequency cut, respectively. This block is different to the "Butterworth band-pass filter" which used in ECG acquisition system that the order of the filters are calculated based on the cut-off frequency and stop frequency parameters. The procedure application is much easier than the use of the filter block such as above Butterworth configuration. This block is packed in the toolkit named as "Digital Filter Design Toolkit". The filtering

During the sound data acquisition, beside the storage for future use, the sound as well as the quality can be checked directly by the hearing of users. To reconstruct the acoustic oscillation, the data conversed from the discrete format to analog wave through 24 bit DAC (Digital to Analog Conversion) sound card integrated in PC. The signal generates the body sound with a speaker with built-in amplifier. The functional procedure is shown in **Figure 15**, where the sound amplitude possibly adjusted with a digital amplifier called as "Set Volume" and generated to the output phone jack through the block of "write". Both blocks are located in Graphics and Sound menu. Both applications based-on use of LINX and LIFA are introduced for examples to visualize the low-cost embedded system design with Arduino and LabVIEW.

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**Figure 15.**

**Figure 14.**

Beside Arduino boards, there are many commercial products are still developing such as Raspberry pi for remote access network or IoT (Internet of Things) system, chipKit for function enhancement, ESP8266 for wifi applications. Recently, to open a change for mobile AI (Artificial Intelligent) system, NVIDIA company released Jetson nanno kit which specified with quad-core CPU and 128-core GPU. Almost of current embedded hardware devices use USB connection with asynchronous communication protocol for data exchange. This means with the definition of NI-VISA which support for the hardware using USB port, the commands and the data can be fullduplex transferred between PC and the embedded hardware devices. The requirement for LabVIEW interface can be solved through firmware library programming.

In the case of large amount of logic components integration required such as parallel filters, numerical array convolution, the embedded system FPGA-based (Field Programmable Gate Array) with LabVIEW can be considered. Unlike the LabVIEW interface package such as LINX and LIFA, the FPGA-based embedded system has to be originated by NI hardware devices or use of other hardware compatible with NI-myRIO platform. With the optimization of logic circuit with specified functions or procedure, the fast response of the FPGA-based embedded systems possibly satisfy the real-time requirement. An example of such application was reported in 2010 with real-time response for DC motor controller design [21].

The advantage of LabVIEW embedded systems that is the enriched update of libraries and block module in each version which support for data processing such as signal processing, image processing, network routing, control system, computer vision, IoT, and more. In large scale system level, when the real-time characteristics is required, the distributed system with multiple computers network possibly the solution. Therefore, for the LabVIEW embedded system in the near future, a trend of functionalizing hardware device is potential development. With the standardization of the data transfer protocol, the computer peripheral design based on embedded system will focus on the firmware and software design rather than the hardware design as before.

With the development of the operating system for smart devices such as Android and iOS, NI LabVIEW also provide a solution that the smart devices users can observe acquired data and control system objects distantly through a service called WebVI, which means the embedded systems in the future can be observed and control through smart devices such as smartphone, tablet when they are connected to internet, an IoT solution of LabVIEW application development [22]. Based-on this enhancement, the category of applications toward IoT system can be widely developed in the near future.
