ECE 477 Digital Systems Senior Design Project Rev 4/12

ECE 477 Digital Systems Senior Design Project Rev 4/12

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Homework 12: Environmental Impact Lifecycle Analysis and Ethical Challenges

Team Code Name: AWESILLOSCOPE Group No. 2

Team Member Completing This Homework: Bo Yuan

E-mail Address of Team Member: yuanb @ purdue.edu

Evaluation:

SCORE

DESCRIPTION

Excellent – among the best papers submitted for this assignment. Very few corrections needed for version submitted in Final Report.

Very good – all requirements aptly met. Minor additions/corrections needed for version submitted in Final Report.

Good – all requirements considered and addressed. Several noteworthy additions/corrections needed for version submitted in Final Report.

Average – all requirements basically met, but some revisions in content should be made for the version submitted in the Final Report.

Marginal – all requirements met at a nominal level. Significant revisions in content should be made for the version submitted in the Final Report.

Below the passing threshold – major revisions required to meet report requirements at a nominal level. Revise and resubmit.

* Resubmissions are due within one week of the date of return, and will be awarded a score of “6” provided all report requirements have been met at a nominal level.

Comments:

1.0  Introduction

AWESILLOSCOPE is a digital oscilloscope with playback function that provides all general feature of a typical oscilloscope, such as sampling analog input, signal processing, auto-scale, cursor, reconstruction and visualization of signals. Additional features include recording and replicating signals as a function generator, import/export waveform data to USB storage device.

As a lab use instrument, AWESILLOSCOPE does not encounter much ethical or safety problem. However, special conditions will be considered and analyzed case by case. For the environmental consideration, the manufacturing process will bring some environmental issues. During normal life cycle, the product has a power waste and the display will rely on VGA, which creates another potential environmental consideration. During disposal process, AWESILLOSCOPE has an easy recyclable package. The internal components however, are electronic wastes. Although implemented with RHoS technology, proper disposal of internal parts is still critical.

2.0  Environmental Impact Analysis

The Manufacturing process of the product will induce hazardous material since PCB is required. The PCB etching will require corrosive and environmental hazard materials such as ferric chloride. To minimize the threat to environment, the life-cycle of the product should be prolonged to reduce the environmental damage.

The components on the PCB also propose critical environmental threats since the production sequence will need hazard materials for etching. However, all the components selected are of RHoS standard, which means during the manufacture process, the use of hazardous material has already been minimized.

Additionally, soldering the parts onto the PCB will require solder. Most of the solders, if not all, contain majorly tin and lead. Overuse of the solder and repeatedly re-construct PCB will not be perceived in an environmental friendly way.

For safety and protection consideration, packaging is required for our product. Steel box is selected to package the compartments and isolate the environmental noise. The steel box is recycled from other product and will be approximately 300 mm * 100mm * 80mm. The production of metal will also inevitably impact the environment.

To minimize the environmental impact, limited materials should be used. For example, the PCB should be as small as possible, and should be easy to fix when certain parts are damaged. Also, the use of parts should be limited and properly disposed if damaged. Finally, it is also important to restrict the material used in packaging the device.

During normal utilization, the power consumption of the device is approximately 2.5 Watts. Although comparatively small than most Oscilloscopes, the device is not so power efficient because most of the power is consumed on the linear regulator. To reduce the unnecessary energy consumption, low voltage linear regulator (5V to 3.3V) is more preferable than the high voltage regulator (12V to 5V). Additionally, in order to generally use the product, a VGA display must be presented. As a result, the VGA screen also becomes part of the power consideration of our project. Normally, external VGA will consume 17-31 Watts if it is a high-efficient LCD screen and 80 Watts if it is an ancient CRT display. To ensure the efficiency of the product, the display is designed as LCD- screen based and on the user manual, LCD screen will be recommended.

When the product enters its disposal phase, during which the product may not be repaired and should be dissembled. Since none of the parts is degradable, all the components should either be recycled or properly disposed. Apparently, the metal box can be easily recycled either for other use or re-production. The other electronic components, however, must be taken to disposal center. The vendor of AWESILLOSCOPE could offer customer return and take the product apart for a more efficient recycle and reuse purpose.

3.0  Ethical Challenges

As laboratory equipment, AWESILLOSCOPE does not have much ethical challenge during its proper use. However, if misused, the project can also create problems for direct user and people related to them.

Laboratory instrument usually requires high accuracy, which could be a potential problem in AWESILLOSCOPE. The sampling sequence will be through ADC and processed within the microprocessor, thus the accuracy of the signal can be interfered by external noise or on-chip interference. During special cases, inaccurate measuring could cause danger to devices and even user. Thus, it is crucial to direct attention to maximize the accuracy of each sampling. The voltage level can be re-adjusted by repeated samples. Since the range of the frequency is less than 200 kHz, low pass digital filter can be implemented to construct the noise rejection mechanism for reducing the possible noise in the sampling process. Moreover, the VGA output should be properly protected so that the VGA output could not be damaged due to potential short circuit of the product. Additionally, operating in an extreme hot or cold environment will impede the performance of the microprocessor, thus may give error results. To ensure the highest performance, user should only utilize the project in a lab and preferably on a stationary platform, also with proper ambient. Additionally, proper warnings should be displayed to tell the user that the results may not always accurate.

Although the product’s output channel seems to be safe to the user (+/- 12 V), it is not always safe for other electronic devices. The accuracy and the output channel need to be carefully measured before output a waveform. The output of the playback channel have to be predictable, otherwise it may easily burn other voltage sensitive components. Moreover, the current of the output channel should not exceed a few milliamps, since high current output will waste energy and endanger current sensitive parts.

From the above ethical consideration, it can be concluded that all output functionality test should be required before output functions (DAC, VGA) being put into use. If the AWESSILOSCOPE can be commonly manufactured, it should be assumed that the VGA can power any display with a VGA connector and no potential threat can be lead to the display device from the AWESILLOSCOPE. Also, it has to be assumed that the voltage output channel can be used as a steady voltage output and low power voltage source. In conclusion, the testing process before output any signal would be necessary and it is also critical to ensure that the outputs can be adaptable with any viable external circuitry. Moreover, it is highly important to measure the accuracy level of the sampling, otherwise it may mislead user to draw wrong conclusions.

4.0  Summary

If consider AWESILLOSCOPE as a commercial product, it has potential ethical and environmental considerations. Major ethical issues include the output signals and compatibility of external device/ circuit, VGA output, and accuracy of sampling. Inappropriate output signal will potentially sabotage the circuit AWESILLOSCOPE connects to, and inaccurate data will let user draw inaccurate conclusion on the signal they measured, thus may lead to problem. For environmental consideration, hazardous impact from PCB manufacture and devices has been minimized through limited size of PCB and limited use of components. Additionally, power consumption is minimized by utilize less high-voltage regulators. Finally, proper disposal is required at the end of life-cycle.

List of References

[1]  Engineering Education Reform: A Trilogy, Frank G. Splittz, Jan. 2003 Retrieved from https://engineering.purdue.edu/ece477/Homework/CommonRefs/enviro_refs.pdf, accessed Apr. 10th, 2012

[2]  Analog, RF and EMC Considerations, James Colotti, Telephonics - Command Systems Division, Copyright Telephonics 2002-2005, revision 4a, retrieved from http://www.ieee.li/pdf/viewgraphs_pwb_design.pdf, accessed Apr. 12th, 2012

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