EE 477 Final Report



Purdue ECE Senior Design Semester Report

|Course Number and Title |ECE 477 Digital Systems Senior Design Project |

|Semester / Year |Fall 2007 |

|Advisors |Profs. Meyer and Johnson |

|Team Number |Team 3 (Humphrey’s Treasure Chest) |

|Project Title |MIDI-Phone |

|Senior Design Students – Team Composition |

|Name |Major |Area(s) of Expertise Utilized in |Expected Graduation Date |

| | |Project | |

|Tony Liechty |CMPE |Software, Hardware |12-16-07 |

|Charles Lan |CMPE |Software |12-16-07 |

|Steven Kingsley |EE |Analog Circuits |12-16-07 |

|Roy Scheck |CMPE |Hardware, Packaging |12-16-07 |

Project Description: Provide a brief (two or more page) technical description of the design project, as outlined below:

a) Summary of the project, including customer, purpose, specifications, and a summary of the approach.

The MIDI-phone is a low cost portable studio used for music creation. To facilitate this purpose a built in microphone transposes the sound from a single note instrument into a MIDI signal. A built in tuning function provides the user the option of tuning his or her instrument to the MIDI-phone for better reception. USB provides a medium for transmission of the MIDI data generated as well as powering the device.

Originally, the MIDI-phone started out as a game idea that would allow users to practice their instruments to songs streaming through a graphical display. After consultation with course staff, several changes were made to the proposal and the final idea of a portable studio emerged. Along with the refined idea, several success criteria for product development were developed and design began based on those criteria.

Block diagrams concerning the major parts of the MIDI-phone necessary were created following the finalization of the MIDI-phone’s functionality. Parts were then chosen based on power consumption and cost in order to satisfy the low-cost and portable description of the MIDI-phone. After the period of part selection, schematics of the entire design were constructed and with the aide of course staff revised until sufficiently meeting all the design criteria. During this time, considerations were also made for various issues ranging from product safety and environmental factors to the manufacturing of the product. Different tasks were then assigned to each individual of the team to speed up the design process. At this point, the construction of the PCB, algorithms for frequency analysis and product packaging started in parallel.

Software design began after receiving and then populating the PCB. This process started with the labeling of all the modules, such as SPI or I2C, on the DSP necessary for product completion. These modules were then worked through one by one until they were able to communicate with their corresponding components outside the DSP. Once all modules worked individually the main program was written utilizing the algorithms designed previously in the project. Algorithm refinement began once a working product was completed. After thoroughly debugging the MIDI-phone it was placed in packaging soon after and declared a success.

b) Description of how the project built upon the knowledge and skills acquired in earlier ECE coursework.

The MIDI-phone drew heavily from previous digital design courses. Basic knowledge of electrical components such as resistors, capacitors and MOSFETs were required to successfully power and use digital components, this knowledge stemmed from ECE 201, 202, 255 and 270. The ability to read datasheets and successfully interpret their meaning, gained from ECE 270, was very important in component selection and schematic creation. The MIDI-phone drew heavily on the assembly learned from previous ECE 362 coursework to access the functionality we needed for the project. C learned from ECE 264 and 368 provided a strong foundation for developing embedded C on the DSP chosen for the MIDI-phone. On a higher level of abstraction, optimization concepts such as loop unrolling learned in ECE468, compilers and ECE437, computer architecture were very helpful in optimizing our program. Finally, filter and amplifier knowledge gained from EE201 and 202 helped immensely in getting our analog microphone data to the DSP.

c) Description of what new technical knowledge and skills, if any, were acquired in doing the project.

The most important new technical skills learned were PCB creation and embedded C. This process took up an immense amount of time, but the skills garnered from its completion were well worth the effort spent. PCB creation helped clarify how the schematics generated translate to an actual representation of the circuit. Embedded C really helped speed up the assembly coding process and helped act as a link between the C we learned in ECE264, Advanced C, and ECE362 very nicely. On a side note, PCB population was also a very interesting experience improving our soldering skills to a new level.

d) Description of how the engineering design process was incorporated into the project. Reference must be made to the following fundamental steps of the design process: establishment of objectives and criteria, analysis, synthesis, construction, testing, and evaluation.

The entire MIDI-phone project was based around the engineering design process. The first part of our process began in brainstorming the ideas we wanted to use as our project. Once we established the MIDI-phone as our project of choice we had to come up with a list of objectives we wanted the project to accomplish. Further brainstorming led to the decision that we wanted user simplicity; this led to the criteria of using USB as it could provide a means of communication and power to our device. Since we needed audio pickup, the criteria of having a built in microphone on the device was included as well.

After having completed the schematic for the MIDI-phone we had to proceed with the synthesis of the PCB to provide a base for our DSP, USB controllers, amplifiers and analog circuitry. When our finished PCB arrived, construction began. The order of construction proceeded by first connecting the power supply, followed by the analog circuit since unlike the digital circuits haven’t been tested since we manufactured it. Following this addition was the DSP. With the addition of the DSP we tested each DSP module and its corresponding external part to guarantee functionality. Finally we added the LCD screen and the SPI to USB connection.

Once everything was constructed, software development and testing was done to ensure the functionality we aimed for worked as intended. Concluding our project we evaluated the finished product to make sure it met the standards set by our project specific success criteria.

e) Summary of how realistic design constraints were incorporated into the project (consideration of most of the following is required: economic, environmental, ethical, health & safety, social, political, sustainability, and manufacturability constraints).

Economic: Each part used for the project was chosen on the criteria to have “just enough” functionality to cover our project goal. As a result, the components used make the MIDI-Phone a very low cost device, and intended for mass production.

Environmental: The Midi-Phone was designed for user simplicity; the packaging is small, but large enough to contain the components reducing waste upon disposal. Additionally it is powered by USB, this constraint we put on ourselves had the added effect on our component selection. We had to choose low powered LCDs and small DSPs that consumed as little power as possible. With a small power requirement, the MIDI-phone proves to be an energy friendly device.

Ethical: The main ethical concerns taken into consideration for the MIDI-phone were the reliability of the product. Testing was done to insure the product worked properly under normal use as advertised.

Health & Safety: No significant health and safety design constraints were made during production of the MIDI-phone.

Social: The goal of the MIDI-phone is to provide a cheaper alternative for many musically inclined individuals to compose their music. Hopefully less fortunate musicians will have the chance to get their work distributed digitally, thus increasing the public awareness of their work.

Political: No significant Political design constraints were made during the production of the MIDI-phone.

Sustainability: The packaging surrounding the MIDI-phone is pretty sturdy reducing the effects of impacts on the product. In terms of use, the MIDI-phone was designed with USB power in mind and because of that, it was assumed that people would be plugging in and pulling out the USB cable often. This assumption influenced the design of the MIDI-phone to only stream audio data. Designing the MIDI-phone in this way removed a lot of the complexity the device could have had with more complex software and hardware.

Manufacturability: All major parts chosen for the MIDI-phone come from well known distributors such as MAXIM, Freescale and CrystalFontz. Additionally, the packaging is small and light weight costing little in terms of materials.

f) Description of the multidisciplinary nature of the project.

The project contained several elements outside of electrical and computer engineering. Acoustic knowledge was vital in considering what users might want in terms of the design as well as handling the audio input from the microphone to the DSP. Technical writing skills were required from the beginning in the creation of all the reports and documents necessary for completion of this project. Additionally, effective communication skills with team members and faculty helped immensely in completing the project on time. Finally, marketing skills were necessary in reducing the cost of the MIDI-phone by the selection of functionality the MIDI-phone supported and the corresponding component and design choices.

g) Description of project deliverables and their final status.

The product deliverable is the MIDI-phone. The MIDI-phone consists of a small PCB encapsulated in a rectangular black plastic casing. Protruding from the product is an LCD screen for tuning and volume control, a volume knob and a USB port. The size of the plastic casing was selected as the smallest available that could hold the MIDI-phone’s PCB and LCD screen. The MIDI-phone is completely operational and in line with the PSSCs selected for this project.

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