Design and Implementation of an Integrated Man-Machine Interface by Touch Panel for an Embedded Electronic Measurement System

Transcription

1 VECIMS 008 IEEE International Conference on Virtual Environments, Human-Computer Interfaces, and Measurement Systems Istambul, Turkey, 4-6 July 008 Design and Implementation of an Integrated Man-Machine Interface by Touch Panel for an Embedded Electronic Measurement System Ying-Wen Bai, Hsing-Eng Lin and Wei-Chun Jau Department of Electronic Engineering, Fu Jen Catholic University Taipei, Taiwan, 4, R.O.C., Abstract In this paper we design and implement an integrated man-machine touch panel interface for an embedded electronic measurement system (EEMS). The interface module of our EEMS includes general electronic measurement instruments such as a waveform generator, an oscilloscope and a power supply. We integrate three man-machine interfaces into one window which works in cooperation with the touch panel. The display function and the input function are controlled by different registers in the touch panel. We also design a corresponding display interface and a corresponding input interface. For the waveform generator we provide a basic waveform output button and include sine, triangle, square and arbitrary waveforms. The arbitrary waveform allows the user to draw on the grid area of the panel by hand. The output voltage and the frequency are adjustable. The oscilloscope has a grid area to show the waveform and the frequency. The power supply has an adjustable estimate to adjust the output voltage. The external interface circuit includes a waveform generator, an oscilloscope and a power supply. The embedded system connects to the external interface circuit through the general purpose input/output port (GPIO). The power supply and the waveform generator provide an output function which outputs the digital data from the embedded system. The digital data are converted by the Digital Analog Converter (DAC) and then the analog signal is output. The oscilloscope has an input function. After the external analog signal has been converted by the Analog Digital Converter (ADC), the digital data are analyzed by the embedded system and displayed in the touch panel. Keywords Embedded System, Touch Panel, Waveform Generator, Oscilloscope, Power Supply. I. ITRODUCTIO In recent years, as it has become more and more convenient to use the Internet, the result has been some changes in the traditional teaching methods. Learning is done not only in the classroom but also through the Internet []. Some designs use remote control and image capture to construct a remote teaching system [], while others use a server that connects to a measurement system in the laboratory for measuring, after inserting the IP []. This design has been extended to let a user conduct electronic experiments outside the laboratory through a distance measurement system by means of both a PC and interface circuit modules [3]. With the development of embedded systems, the architecture of the remote measurement system has become a better choice, because the physical size of an embedded system is small, it is portable; it requires low power consumption and has network functions [4]. Some designs use an embedded Linux system to construct the control program for the Direct Current Motor Control System in the embedded system. Because the embedded Linux system is suitable for many platforms, in the future it can be modified to include more complicated controls [5]. There are many advantages, such as low cost, high efficiency and low power consumption, when we implement an electronic measurement system by way of an embedded system to connect to the Internet [6]. In addition, we can obtain an automatic engineering analysis by using the embedded system software and the hardware constructed with a DSP chip and a touch panel [7]. From the operation point of view, the touch panel not only becomes a new input interface but also reduces the size of the system an increase its efficiency. Recently touch panels have come to be used in some applications [8] [9]. The electronic instruments in the electronic laboratory are traditionally always operated by using buttons or knobs. Some new electronic instruments use computers to integrate the man-machine interface. Their design only includes waveform generation and oscilloscope. Some designs provide a Windows-based operation interface. However, they can t simultaneously display two or more operation interfaces of instruments in the same Window. [0]. Some electronic instruments are based on an embedded system and operate through computer monitoring []. However, their designs are of a larger size than our design due to our use of the touch panel. The man-machine interface using a touch panel can replace the button and the knob, so that the size is reduced and operation becomes more convenient. In Section II of this paper we introduce the basic design of a man-machine interface for a touch panel of the EEMS. In Section III we introduce a man-machine interface for a touch panel of the EEMS. In Section IV we show the results, and in Section V we draw our conclusions. II. THE BASIC DESIG OF A MA-MACHIE ITERFACE FOR A TOUCH PAEL When the embedded system is equipped with a touch panel, the port of display interface uses the LCD register and the input interface consisting of the ADC and the interrupt register. Hence we must design the display interface and the input interface at the same time when we design the man-machine interface. In Fig. we have three areas, two estimates and one button that the user can operate. Therefore we have to include these three areas on the input interface. The final man-machine interface needs to superimpose the display /08/$ IEEE 3

2 interface and the input interface on each other. Finally we have to test whether there are any errors after superimposing the two interfaces. into the drawing mode, because the parameter was set equal to. The user can use a piecewise linear algorithm to draw the arbitrary waveform. To select the adjustable mode again, he just needs to click the basic waveform output button. Display interface Run Superimposed 3 Input interface Start Set con = Touch? Y con =? con =? Y Y Use Adjustable mode Use Drawing mode Run Man - machine interface Choose Y basic waveform output? Set con = Fig.. The basic design method of a man-machine interface for a touch panel. Fig. shows the design of the data buffer. We use a 4.3-inch touch panel whose size is about 60 cm. When compared with the general size of electronic measure instruments, this panel is very small. Therefore we use a multi-function method to increase the availability of the touch panel. The left side of Fig. shows the adjustable mode of the waveform generator. In the same area, we can design the drawing mode. When the user clicks on the basic waveform output button, the area of the waveform generator is converted into the adjustable mode, and when he clicks on the arbitrary waveform output button, the area of the waveform generator is converted into the drawing mode. Adjustable mode Raise Reduce The same area Drawing mode Fig.. The design of adjustable and drawing modes. Fig. 3 shows the flow chart of the operation of the data buffer, which corresponds to the design of the data buffer in Fig.. We use a parameter which we will name con, to control the switch for the two modes of the data buffer. The initialization of the parameter con is equal to, which is the adjustable mode. The user can obtain other waveforms from the basic waveform. If he wants to change the adjustable mode to the drawing mode, he needs to click on the arbitrary waveform output button. The parameter con will be set equal to, and when the user clicks on the area of the waveform generator once again it changes the adjustable mode Choose Y arbitrary mode? Set con = Fig. 3. The flow chart of the operation of the data buffer. Fig. 4 shows the method that our design uses to reduce the computation of the embedded system. On the left side of Fig. 4 we see that if we use the x and the y to decide the case, then in every action there be two results which will cause malfunction. if ( x > 0 & y > 0) if ( x < 0 & y > 0) if ( x > 0 & y < 0) if ( x < 0 & y < 0) y Zoom in ( x, y ) θ ( 0, 0 ) x Zoom out Fig. 4. Malfunction of the use of the xy -plane. Fig. 5 shows the method that will be used instinctively. By rotating the xy -plane 45 degrees it becomes the αβ -plane. The four quadrants that the α -axis and the β -axis cut just correspond to four directions. But if we were to rotate xy -plane each time. We would need to make additional computation Because α = x cosθ, β = ysinθ we will have two multiplications each time we rotate the axis. If we look up the table, this will occupy part of the memory. There is thus a burden on the embedded system no matter whether we compute directly or look up the table. 3

3 Zoom in ( 0, 0 ) Zoom out α ( α, β ) β if ( α > 0 & β > 0) if ( α > 0 & β < 0) if ( α < 0 & β < 0) if ( α < 0 & β > 0) Fig. 5. The method of rotating the xy -plane to become the αβ -plane. Fig. 6 shows the method we use. The α -axis and the β -axis are judged to use the axes slope equal to and - instead. Because judging the comparative equation only uses the subtraction, the method we use not only judges > m > but also judges x > 0 and x < 0 to improve the accuracy. With this method, we reduce the burden on the embedded system, because m = y is the only division of the main x computation. y Zoom in m = ( x, y ) ( 0, 0 ) x Zoom out m = if ( > m > & x > 0) if ( > m > & x < 0) if ( m < m > & y > 0) if ( m < m > & y < 0) Fig. 6. The method of using the xy -plane and the slope. Fig. 7 shows the method we have designed to re-draw the estimate. If Fig. 7(a) is the result of the preceding execution, the user adjusts the red-bar to the position x. The whole estimate is divided into two parts. One is the red area, and the other the black area. Our design doesn t estimate when the user adjusts the red-bar again, and it will cause the picture to remain. Fig. 7(b) shows the method we use to re-draw the estimate if the user wants to adjust the red-bar from x. This operation increases the length of the red-bar. We just need to draw red from x if the user wants to adjusts the red-bar from x. This operation decreases the length of the red-bar and we just need to draw black from x. Using this method there is no need to draw red and black from 0 to 00, and this reduces the time for computation. 0 x 00 0 x x 00 Fig. 7. The design estimate method. Fig. 8 shows the method we have designed to re-draw the grid area of the oscilloscope. Fig. 8(a) shows the grid area of the oscilloscope before re-drawing. Because we can move, zoom in or zoom out the waveform on the time domain in the oscilloscope, there will be a broken image if the grid area of the oscilloscope is not re-drawn. Fig. 8(b) shows the grid area re-drawn and filled up by the black area (method I). Even though there is a broken image, the processing is very fast. Fig. 8(c) shows the method of re-drawing the grid area of the background (method II). We get an intact image after re-drawing the grid area of the background. But as we have to search the relevant area of the background, so the drawing takes more time. Fig. 8(d) shows the re-drawing if the whole background (method III). We also get an intact image, but as we need not search the relevant area, the processing is faster than in method II. Yet the processing is slower than in method I, because the array of the whole background is very large. (a) (c) Fig. 8. (a) The grid area before re-drawing. (b) Method I: Filling up by the black area. (c) Method II: Re-drawing the grid area of the background. (d) Method III: Re-drawing the whole background. (b) (d) III. THE DISPLAY ITERFACE OF THE EEMS WITH THE TOUCH PAEL Fig. 9 shows the display interface of the EEMS we designed. We divide the display interface on the touch panel into three parts. The grid area in the upper left corner and in the middle is for the waveform generator, the grid area in the lower left corner and in the middle is for the oscilloscope, and the left side is for the power supply. The waveform generator sets the basic waveform output button to include sine, triangle and square. When the user selects and clicks the button, the output waveform is shown on the grid area of the waveform generator. In addition to the basic waveform output button we have designed an arbitrary waveform output button. When the user touches this button, the grid area allows the waveform to be drawn by hand. After drawing the waveform the user touches the Run button. Then the embedded system sends the data to the external interface circuit. There is also an up-and-down button to adjust the output frequency. The oscilloscope sets the frequency display and the Run button. There is also a button not only to show the waveform but also to zoom-out and zoom-in the waveform in the time domain. The operator uses the grid area to zoom-out and zoom-in the waveform voltage and to shift within the time domain. The power supply sets two estimates to control the two output 33

4 ports. When the user adjusts the estimate, the output voltage is immediately displayed in the bottom area. Fig. 9. The interface of the EEMS. Fig. 0 shows the input interface of the EEMS. It corresponds to the display interface of the EEMS. We use 5 areas to represent the display interface. Area is the button used for changing into the arbitrary waveform mode. Areas to 4 are the buttons for selecting the basic output waveforms sine, triangle, and square. Areas 5 and 6 are up-and-down buttons for adjusting the output frequency. Area 7 is the Run button for the embedded system to send the data to the external interface circuit. Area 8 is the Reset button of the waveform generator. Areas 9 and 0 are the buttons for zooming-out and zooming-in the waveform in the time domain. Area is the Run button of the oscilloscope. Area (6) is the area for the user to draw the arbitrary waveform in the drawing mode or to adjust the basic waveform in the adjustable mode. Area 3 is the area for adjusting the voltage of the oscilloscope. The downward, upward, left and right operations implement the zoom-in, zoom-out, shift-left and shift-right of the waveform. Areas 4 and 5 are estimates for adjusting the output voltage of the power supply. or Raise Raise use a data buffer both to raise the output bandwidth and to control the output frequency. Then the DAC converts the digital data into the analog signal. Finally, the analog signal is output after the amplifier has adjusted the voltage of the analog signal to what we want. For the oscilloscope module there is also a data buffer. We use the data to improve the bandwidth of the measurement. The input signal has its voltage adjusted by the amplifier to be suitable for the ADC. Then the ADC converts the input signal into digital data. The digital data are stored in the data buffer. Finally, the embedded system loads the data from the data buffer. The three modules share the general purpose input-output port (GPIO). To prevent mutual interference, we set a data buffer into the power supply module. Then the power supply outputs the voltage after being adjusted by the DAC and the amplifier. User Touch panel GPIO Embedded system Waveform generator Data DAC OP Output buffer Data buffer Data buffer Oscilloscope ADC Power supply DAC OP Driver Input Output Fig.. The hardware architecture of the EEMS. IV. IMPLEMETATIO RESULTS Fig. shows the electronic experiment with the prototype of our EEMS. The whole experiment is constructed in the embedded system ARM-9. We complete the implementation of the EEMS by integrating the embedded system ARM-9 and the external interface circuit. It now consists of the touch panel for inputting and outputting, the embedded system that is the main control of the EEMS and the external interface circuit that is constructed using a PCB. In addition, we inspect the output waveform by using a general oscilloscope. Reduce Zoom - in Zoom - out Reduce Interfacecircuit Touch panel Check the waveform Embedded system Fig. 0. The interface of the EEMS. Fig. shows the hardware architecture of the EEMS. We complete the hardware architecture of the EEMS with the integration of the touch panel, the embedded system and the external interface circuit that we designed. The user controls the embedded system and the external transform circuit through the man-machine interface on the touch panel. The architecture of the external interface circuit consists of the waveform generator module, the oscilloscope module and the power supply module. For the waveform generator module we Fig.. The example of our EEMS for the electronic experiment. Table is a specification of the EEMS we have designed. We construct only one channel to the waveform generator and the oscilloscope, so that we will have a space to construct the power supply. For the bandwidth we produce a trigger using 34

5 an oscillator with 80 MHz. For the waveform generator, if we construct one cycle of the output waveform with twenty points, 4 MHz is the highest frequency for the output waveform. For the oscilloscope, if we construct one cycle of the input waveform with ten points, 8 MHz is the highest possible frequency for the input waveform. Then we use only 8 bits per of the touch panel to design the man-machine interface, because using few bits reduces the complexity when designing a cycle. For the voltage range, we adopt 5V which is commonly used for general electronic experiments. The vertical resolution used for displaying the waveform is about 70mVpp per and the horizontal resolution is about 40KHz per. Table. The specification of the EEMS we have designed. Waveform Power Oscilloscope Generator Supply Channels Bandwidth 8MHz 8MHz Waveform Resolution 8Bit 8Bit 8Bit Voltage -5V~5V -5V~5V 0~5V Range Vertical Resolution Horizontal Resolution 70mVpp per 40KHz per 70mVpp per 40KHz per 30mV per Fig. 3 shows the man-machine interface for a touch panel of our EEMS. We use the 4.3-inch touch panel which has s and is about mm in size. The waveform is the output waveform on the grid area over the upper side of the touch panel. The output waveform is shown on the grid area with red dots. The output waveform is outputting the triangle waveform at 80 MHz. Using the differential circuit we use an oscilloscope to show the input waveform on the grid area over the lower side of the touch panel. The digital data are also shown on the grid area with red dots. The embedded system will not fill the gap between each dot so as to prevent errors in the original input signal. The right side of Fig. 6 is the power supply estimate. Two estimates mean that the design has two power supplies and can output the voltage at the same time. When the user adjusts the estimate, the output voltage is immediately displayed. mm 3mm 6mm 03mm 33mm 3mm Fig. 3. The man-machine interface for a touch panel of our EEMS. Fig. 4 shows the comparison of the electronic experiment result of our EEMS and that of general instruments. Fig. 4(a) shows the inverting amplifier. R = KΩ and R = KΩ. We vo R use the amplification = = where the phase margin v R I is 90. Fig. 4(c) shows the result of measuring the inverting amplifier. We use the sine wave produced by the waveform generator we have designed with a frequency of 380 KHz, and the amplitude is 63.8 Vpp. Then we show the waveform on the oscilloscope we have designed after the sine wave has passed through the inverting amplifier and has been amplified. The voltage is output by the waveform generator and measured by the oscilloscope. We can also get the vo 6.59 amplification = = where the phase margin is v v I R 0V I (a) (c) (e) - R 5V - 5V v O v I (t) C 0V (b) (d) (f) - 5V - 5V v O (t) Fig. 4. The comparison of our EEMS and that of general instruments. (a) The inverting amplifier. (b) The differentiator. (c)measuring the inverting amplifier using our EEMS. (d) Measuring the differentiator using our EEMS. (e)verifying the waveform using the general oscilloscope. (f) Verifying the waveform using the general oscilloscope Fig. 4(e) shows that we verify the waveform by the general oscilloscope. Fig. 4(b) shows the differentiator. R = 0KΩ and C = 0. µ. Fig. 4(d) shows the result of measuring the differentiator. We obtain the triangle wave that be produced by the waveform generator with a frequency of 380 KHz where the amplitude is 9.84 Vpp. Then we show the 35

6 waveform on the oscilloscope after the triangle wave has passed through the differentiator and has been amplified. We can observe the waveform on the oscilloscope as a square wave with an inverted phase. Fig. 4(f) shows that we verify the waveform by the general oscilloscope. Table shows the comparison of our design with three other products. We can see that the operation area of the touch panel of our EEMS is smaller than those of the other three instruments. The operation area includes the displays, buttons and knobs. If we compare the total operation area, that of our EEMS is ten times smaller than those of the three other products. As for the performance, their general waveform generator has the basic waveform which our EEMS also has. Using the touch panel, we add a function so that the user can draw an arbitrary waveform by hand. We also use the touch panel to replace buttons and knobs to reduce the operation area of our EEMS significantly. Table. Comparison of our design and three other products. Waveform generator Our design Product A Operation area 30mm 70mm 80mm 0mm Basic waveform Sine, Triangle, Square Sine, Triangle, Square, DC Arbitrary waveform Drawn by hand Default Channels Oscilloscope Our design Product B Operation area 30mm 70mm 35mm 300mm Channels Power Supply Our design Product C Operation area 30mm 60mm 30mm 0mm Channels Main operation method Total operation area Touch panel Button, Knob 60 cm 854 cm V. COCLUSIO We have designed the interface of our EEMS by using a touch panel. Our EEMS includes the waveform generator, oscilloscope and power supply. In addition to the general functions like outputting the basic waveform, adjusting the waveform and adjusting the voltage, we have also added several functions like drawing the arbitrary waveform. Thus our EEMS is easier to use. By using the touch panel as input and output interface we reduce the operation area of our EEMS significantly, because the touch panel replaces the buttons and knobs of the traditional instruments. The function of the embedded system is very complete. Beside the touch panel and the GPIO we also use the network function in the embedded system. Through the network function we have made the EEMS portable and remote. It can be a server or a client that students or engineers can use to send or interchange measuring data. The bandwidth of the waveform generator and the oscilloscope of our EEMS is low. In the future we can increase the bandwidth by many ways. We can also replace the ADC, DAC and oscillator to achieve higher speed, increase the sample and convert frequency. The voltage of the power supply can also be increased if we increase the Vcc of the amplifier of the external interface circuit. We can add more functions on the touch panel, such as the software buttons, for a more natural operation. Our current functions on the touch panel just offer ways to input the setting. To further reduce the operation area we can also design a tree system for the man-machine interface. All these ways we can study and design in the future. REFERECES [] T. Yoshino, J. Munemori, T. Yuizono, Y. agasawa, S. Ito and K. Yunokuchi, Development and application of a distance learning support system using personal computers via the Internet, 999 International Conference on Parallel Processing, pp , Sept []. Ranaldo, S. Rapuano, M. Riccio, F. Zoino, Remote Control and Video Capturing of Electronic Instrumentation for Distance Learning, IEEE Transactions on Instrumentation and Measurement, Volume 56, pp.49-48, Aug [3] Ying-Wen Bai and Hong-Gi Wei, Design and implementation of a wireless remote measurement system, Instrumentation and Measurement Technology Conference, 00. 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