ELEC424 Project: Tilt 1

1. Goal and Grading

1.  Design the circuit and layout of your PCB. The PCB holds a microcontroller (TI MSP430), multiple sensors, and simple user interfaces such as buttons and LEDs.
2.  Send your PCB design to PCBExpress.com to fabricate your board. Assemble the board by soldering all the components to the board.
3. Port a real-time operating system to the system. The source code of the operating system is available.
4. Develop software to recognize and display board tilting. You will gain extra credits by enabling manipulation recognition using an existing algorithm.
5. Design and carry out a user evaluation of the final system.

The project will be graded by two factors: 1) how well the embedded system realizes the intended function: a) correctness of the realized function (50%); b) power efficiency of the realization (25%); and 3) the cost of the realization (25%) and 2) how well you performed during each of the four steps described (25% each).  The two factors are multiplicative. For example, if you get 90% for the first and 80% for the second, your final grade will be 90%*80%=72%. For another example, if you only achieve the first three steps, you will get at most 75% of the second factor. Because the design is incomplete, you need to write about the exact function your system is designed to achieve and explain how; and analyze the cost and efficiency of your design, in order to get as much as possible for the first factor.

2. Tasks

You will complete the following tasks in this project.

1)      Architecture

You will decide the major components on the board for the basic tilt/orientation recognition and user interfaces: will you need one or two accelerometers? Will you need the compass? How many buttons will you need for input? How many and what color of LEDs will you need for on board display?

2)      Circuit schematic

After the board architecture is settled, you will design the circuit schematic in EAGLE PCB following the reference schematics and datasheets provided in the next section. Orbit-EDU is also a good reference for your design.

3)      PCB layout

Having the circuit schematic correct and complete, you can design the PCB layout and routing. You will decide the locations of all components (except the MSP430, the two accelerometers and the compass that are supposed to be prefixed in their locations) and the routes of wires connecting them. Please carefully read through the notes in Section 5 before you start. Make sure your design passes the rule check in EAGLE PCB. A safe way is to import the rules used in Orbit-EDU and use those rules.

4)      Assembly

When your PCB design is ready, you will prepare various files about the design and send them to PCB Express to manufacture the board. Afterwards, the MSP430 and the motion sensors will be machine assembled by a local company, and you will assemble all other components onto the board by hand.

5)      Operating system

Learn to program the MSP430 from a computer through the programming interface. Test your board with simple operations like blinking the LEDs to make sure the board works. Port an open-source operating system to MSP430. Design test cases to verify the installation.

6)      Tilt/orientation recognition

Design and implement the software for MSP430 to detect tilt/orientation of the board. For extra credits, you will implement an existing gesture recognition algorithm in MSP430 to recognition various physical manipulation of the board.

7)      User evaluation

As the final step, you need to evaluate your "product" with a group of users. Each other team will contribute one to the group. Although the number of users may be small, please try to apply what you have learned from the class. You need to design and carry out a user study. The user study may have several components, leveraging survey, individual interview, and focus group discussion. You need to evaluate the usability (including correctness of functions, responsiveness, and ease-of-use) and aesthetic design of your "product". You need to carefully design the questions and make sure they are valid and invite useful information. Finally, you need to make valid and insightful conclusions regarding your "product", regarding its weakness, strength, and ways to improve it. Your user evaluation will be graded NOT based on how highly your users think of your "product." Instead, it will be graded based on 1) the quality of user study design, including questions you ask; and 2) what valid and insightful conclusions you draw.

3. Further Readings

1) PCB Design

More information can be found here.

2) Programming OrbitEDU

To learn necessary information about MSP430, please read  Chapters 1, 2, 3, 4, 9, 11, and 17 of its User Guide.

You need to program your design using IAR Embedded Workbench. See here for a simple tutorial how to start with IAR Embedded Workbench. Since your design is similar to OrbitEDU, you can start with the following OrbitEDU example code.

Texas Instruments provides useful example code too.

To learn more C programming of MSP430 with IAR Embedded Workbench, read MSP430 IAR C/C++ Compiler reference guide.

3) µC/OS-II

Datasheet from Micrium. There is a good book about it. You may want to read Chapters 1, 2, and 13.

We have two tutorials to work with µC/OS-II on OrbitEDU using IAR Embedded Workbench and GNU/Linux, respectively. We recommend you use IAR Embedded Workbench for the project.

4.Administrative Information

TA: Jiayang Liu
DH3040, jiayang AT rice.edu

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