ECE 477 Digital Systems Senior Design Project Rev 8/11

ECE 477 Digital Systems Senior Design Project Rev 8/11

Homework 3: Design Constraint Analysis and Component Selection Rationale

Team Code Name: ___Home Enhancement Suite______Group No. __10__

Team Member Completing This Homework: ____Nathan Irvin______

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

Evaluation:

SCORE / DESCRIPTION
10 / Excellent – among the best papers submitted for this assignment. Very few corrections needed for version submitted in Final Report.
9 / Very good – all requirements aptly met. Minor additions/corrections needed for version submitted in Final Report.
8 / Good – all requirements considered and addressed. Several noteworthy additions/corrections needed for version submitted in Final Report.
7 / Average – all requirements basically met, but some revisions in content should be made for the version submitted in the Final Report.
6 / 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:

Comments from the grader will be inserted here.

1.0  Introduction

The Home Enhancement Suite is a package that will control various aspects of a room in an autonomous fashion when a user is recognized through RFID. Currently, there are home automation kits available, but generally these do not incorporate different settings for different people. The Home Enhancement Suite will allow a user to automate the lighting as well as set up an HDMI product, such as a television, to their favorite channel and volume.

The Suite will also feature software that runs on a home PC that will allow the user to quickly and easily set-up the user profiles as well as change the settings as desired. The software program in conjunction with the room unit will work seamlessly together to provide users with a unique experience of automation.

The design itself will be centered around a microcontroller that controls each of the systems including X10 communication, CEC-HDMI communication, and working an electronic door lock as well as RFID interpretation. The micro will also communicate with a PC, through ethernet, running a new software program that allows users to adjust and save their settings.

Updated PSSCs

1. An ability to detect a user based on RFID and determine which user has priority, displaying the user's identity on an LCD.
2. An ability to adjust the light intensity to match a user’s settings through X10 protocol.
3. An ability to adjust a television set or other HDMI device using CEC-HDMI protocol, to a user's preferred settings. (ON/OFF, Channel, Volume)
4. An ability to unlock a door when an appropriate RFID is present.
5. An ability to select/set preferred settings through a computer program and the ability to save the "light settings" with the press of a button.

For an updated block diagram, please see Appendix B.

1.0  Design Constraint Analysis

The main tasks that the Home Enhancement Suite must accomplish are the ability to communicate through X10 and CEC-HDMI, control of an electronic door lock, interpretation of an RFID tag, and communication with a PC running a program that is also hosting the users’ settings. The micro will be in charge of all communication with peripherals and the control of the “fail-safe” electric strike. The program will be in charge of interpreting the users’ settings and communicating properly with the micro.

Cost is not a major concern as other home automation kits available are very expensive. This system should be a much more affordable option and allow the user to choose what features they want to purchase and how many rooms they would like to expand to. The packaging should be fairly simple and unobtrusive when placed in a room. As a prototype, cosmetics are not a priority, but the ability for it to be visually appealing in a final design should have some merit. The design is not going to be mobile and will therefore be running off of a home’s standard AC. For this reason, efficiency is not a primary concern, but the idea of home automation lends to a more efficient environment, so the design should be conscientious of this fact as well.

1.01 Computation Requirements

The Home Enhancement Suite, or simply referred to as “the Suite” for the remainder of this document, will have to do various computational tasks. To begin with, it must recognize an RFID obtained via a reader and check that the ID is an acceptable user. It must then unlock the door if necessary followed immediately by executing the proper X10 protocol to adjust the light intensity to the user’s preferred settings. The Suite must also execute the proper CEC-HDMI protocol to set up the television to the user’s preferred settings. In addition, the Suite will also be in charge of interpreting the intensity setting, should the user like to immediately save the current setup to their profile. All settings will be stored on a local PC and the Suite will communicate with the PC via ethernet. In addition, the Suite must output the current “active” user on an LCD display.

1.02 Interface Requirements

The Suite will need to interface with many modules through various connections/ports. The RFID readers will be connected through USB and therefore the Suite will require a total of 3 USB ports (2 for the optional exterior door and one located centrally in the room). It will connect to a PL513 via an RJ-11 telephone jack and connect to the host PC through ethernet. Finally, the Suite will connect to an electric strike through a standard 2-pin header. The Suite will feature a microcontroller that supports ethernet and at least one USB connection. The additional On-chip Peripheral requirements will be explained in section 2.03 of this analysis. Optical isolation will be utilized in the electric strike drive circuit as protection against any malfunction of the strike itself.

1.03 On-Chip Peripheral Requirements

The Suite will require a minimum of 1 Ethernet, 1 USB, 1 ADC, 3 General Purpose I/O pins, and 2 SPI. The general purpose I/Os will be used to control the electric strike and communicate via HDMI using the CEC protocol as well as accept the “user save” function that allows the user to press a button and save the current light setting. One of the SPI will be used to execute the X10 protocol and the other will communicate with the LCD display module. The ADC will be used to interpret the ambient light reading. Finally, the USB will connect to a USB hub control expanding it to the required 3 USB ports for the Suite.

1.04 Off-Chip Peripheral Requirements

The Suite will require a few additional Off-Chip peripherals. The main one is a PLIX IC that will be interfaced with through one of the SPI. This chip will then connect via an RJ-11 telephone jack to the PL513 which is connected to the AC power line for communication with the X10 protocol. This portion of the system will control the intensity of the light. An analog-to-digital converter will be used if not available on-chip to convert the analog signal registered by an ambient light sensor. A USB hub controller IC will be used to create 2 additional USB ports which will receive the RFID reader data.

1.05 Power Constraints

The Suite will be A.C. powered only and there will not be any major concerns with current draw. We will implement an on-board power supply, such that we have access to VUNREG and can utilize it to charge a capacitor that will be discharged to provide the necessary current burden to operate the electric strike for unlocking the door. The PLIX IC requires 5 VDC, while the USB controllers and micros selected require 3.3 VDC and are more efficient. As cost is not of primary concern, the Suite will feature both regulators, operating off of VUNREG to supply the necessary components.

1.06 Packaging Constraints

There are no major packaging-related constraints for this system. The finished product should be unobtrusive and fit on a normal desk top or on top of a typical entertainment stand. The system is not going to be portable and therefore does not have any strict dimension tolerances or structural demands.

1.07 Cost Constraints

Currently there are “Home automation systems” available that can do some of the things that the Suite is capable of doing, but there are no products that are identical in nature. Many of the other systems control aspects of the home that the Suite does not address as they are not prudent and are simply a cost that can be saved. There is a product developed by HomeSeer [1] that requires the purchase of software for roughly $200 and then the purchase of various controllers to add to the system. The overall cost would end up being roughly $1000 to implement the software, RFID receivers and all necessary components for X10 communication. The Home Enhancement Suite will handle those features and more without the purchase of additional items, but will be limited in overall execution and abilities and therefore it is important that the cost be kept well under the current market. The Suite, including all of the necessary components should be available for roughly $600.

2.0  Component Selection Rationale

The Suite’s main component, the microcontroller, does not have a lot of very specific design constraints. Speed is not of much importance, so the previously mentioned peripherals were the driving force for selection. Two options were considered as candidates which included the PIC32MX664F064L(PIC32)[2] from Microchip and the AT32UC3A0512(AT32)[3] from Atmel. Both were selected based on the peripherals including the necessary ethernet, SPI, and one on-board USB. Both have sufficient flash with plenty of overhead to accommodate any additional features added to the Suite. The approximate cost for the PIC32 is $7.10 and the approximate cost for the AT32 is not available, but samples are and the cost is expected to be similar. Currently, the PIC32 has been selected for the prototype.

The next major component choice is the PLIX chip, or Power Line Interface for X-10. This IC is currently only being produced by one company, Micromint USA [4], and therefore it has not been compared to any other candidates. If the IC is not available, it can be created from passive components and some very involved programming. The PLIX chip is designed to eliminate the issues and concerns with using a microcontroller to communicate using the X-10 protocol.

An additional component that required some consideration is the ambient light sensor. Vishay[5] offers various surface mount options including the TEMT6000 and TEMT6200. For our expected illuminance, both offer similar characteristics and can be obtained for less than $1.50 through various suppliers.

The last major component being addressed in this report is a USB controller IC. There are many options available so a low-cost option is being pursued. Because the microcontroller itself has one USB included, the Suite requires two additional ports. There are USB controllers that are capable of adding these and interfacing with the micro via SPI, but there are also hub chips available. One option would be to interface the on-chip USB with a hub controller to give 4 downstream ports, which is more than enough. Atmel offers the AT43301[6], which is a low-cost USB Hub Controller and does exactly as described above. Another available option is offered by Texas Instruments in the TUSB2046B[7] package. This chip also does exactly as described above in a different footprint. Because they are comparable in functionality, and price is not of utmost concern, a final decision will be made based on available real-estate on the PCB. For a current proposal, the TUSB2046B will be selected.

3.0  Summary

The Home Enhancement Suite will bring a user one step-closer to automated, seamless living throughout the home. The user will be able to easily enter and walk throughout the home as it configures to their pre-configured settings. The Suite will interface with already existing technology through various ports and the microcontroller selected to control the system is the PIC32MX664F064L. A PLIX interface chip will be utilized in conjunction with the X-10 protocol to control the lights. All other circuit components are readily available through various manufacturers. For the prototype, there are no strict price or packaging constraints as it is assumed the final product will be well under the current home automation systems available.
List of References

[1]  HomeSeer [Online]. Available: http://www.homeseer.com [Accessed: Jan. 30, 2012]

[2]  PIC32MX664F064L [Online]. Available: http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en552074 [Accessed: Jan. 28, 2012]

[3]  Atmel Corporation - Atmel AVR 8- and 32- bit Microcontrollers - 32-bit AVR UC3 [Online]. Available: http://www.atmel.com/dyn/products/product_card.asp?category_id=163&family_id=607&subfamily_id=2138&part_id=4117 [Accessed: Jan. 28, 2012]

[4]  Power Line Interface for X-10 (PLIX) [Online]. Available: http://www.micromint.com/index.php/Micromint-Chips/plix.html [Accessed: Jan 26, 2012]

[5]  Vishay Broadens Portfolio of Ambient Light Sensors with Surface-Mount 0805 Devices [Online]. Available: http://www.vishay.com/company/press/releases/2006/060707sensors/ [Accessed: Jan 31, 2012]