1. ECE 477 Design Review Group 3  Fall 2005

2. Outline Project overview Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
PCB layout
Software design/development status
Project completion timeline
Questions / discussion

3. Project Overview
P.E.T. Express will use RF-ID technology to control access through a common pet door. The P.E.T. Express will utilize a Motorola MC9S12NE64 and will include feedback ability through an LCD display, embedded web server, and keypad input. These features, along with software controlled permissions, will control the locking action of the pet door through the use of pulling solenoids.

4. Project-Specific Success Criteria
Ability to unlock pet door in response to RFID tag detection or manual override pushbutton.
Ability to configure pet door and monitor its status via an embedded web server.
Ability to provide audio feedback ("beep") in response to RFID tag detection.
Ability to display pet door status locally on an LCD (suggest using RPG to scroll/select).
Ability to continue operation in the event of A.C. power failure (battery backup).

5. Block Diagram

6. Component Selection Rationale
Microcontroller – MC9HS12NE64 (112 pin)
Adequate RAM and FLASH
2 SCI ports, Embedded Ethernet, Timer module
Prior knowledge of product and available support
LCD – Crystalfontz CFA-634
SCI output
4x20 character display
RFID - Intersoft WM-RO-MR2
SCI output, customizable antennae
Adequate transmission range (~10”)

7. Component Selection Rationale
Keypad and Encoder – Allelectronics KP-23 & Fairchild MM74C922
Adequate functionality (16 keys)
Reasonable encoding (4 bits)
Solenoid – Allelectronics SOL-58
Adequate range of motion
Adequate pulling force
Spring return
Power Supply - PST-AC W Adjustable Output
Adjustable output voltages
Adequate current rating (6.8 A)
Battery - 12V / 7Ah Sealed Lead Acid Battery
Adequate voltage and current supply
Able to be charged easily

8. Packaging Design
P.E.T. Express will consist of two main sections: a pet door and a control module.
The pet door will house the solenoids and the RF-ID antenna will wrap around it. The power and control lines for the solenoids and the antenna lead will run from the control module to the pet door.
The control module will house the PCB, external circuitry, and all the associated peripheral devices. A power cord from the wall and control lines out will attach to the outside. It will be of an appropriate size to mount to a normal door.

9. Schematic/Theory of Operation
Power System Overview
18V Input Supply – Supply Voltage from AC switching power supply.
15V Linear Regulator – Converts 18V to 15V using LM317; Used for battery charging circuit and solenoid power.
9.6V Linear Regulator – Converts 15V to 9.6V using LM317; Used as input to RF Reader.
5V Switching Regulator – Converts 15V to 5V using LT1076; Used as input to LCD, RS232 level translator, speaker, and solenoid driver circuits.
3.3V Step-Down Regulator – Converts 5V to 3.3V using LTC1174; Used as input to the microcontroller, keypad encoder and Ethernet transformer.
18V Input Supply
15V Regulator
9.6V Regulator
5V Regulator
3.3V Regulator

10. Schematic/Theory of Operation
15V Linear Voltage Regulator
Incorporates a fuse
Overload protection circuitry
Battery trickle charger
Dual voltage bus depending on operating mode

11. Schematic/Theory of Operation
9.6V Linear Voltage Regulator
15V input
Overload protection circuitry

12. Schematic/Theory of Operation
5V Switching Voltage Regulator
Switching voltage regulator
High current output
Resistant to input voltage variation

13. Schematic/Theory of Operation
3.3V Power Supply Regulator
5V input voltage
Overload protection circuitry

14. Schematic/Theory of Operation
Microcontroller
112 pin package
Controls all peripherals
64K RAM available

15. Schematic/Theory of Operation
Ethernet Controller
Transforms Ethernet signal for transmission
Capable of full duplex operation
Contains LEDs for visual feedback verification

16. Schematic/Theory of Operation
RF-ID Reader
Onboard tunable antenna connection
Signal receive interrupt
1ms delay before half-duplex RS232 transmission
Operating range of ~10 inches

17. Schematic/Theory of Operation
LCD
4x20 character display
Separate LED backlight turn-on
Half-duplex RS232 communication

18. Schematic/Theory of Operation
Keypad Circuitry
Versatile 16 key keypad
4-bit coder to reduce I/O pin usage
Data-Available interrupt pin

19. Schematic/Theory of Operation

20. Schematic/Theory of Operation
The RF-ID reader will send an interrupt to the microcontroller when a tag comes into range that will enable the SCI port for transmission via RS232 connectivity.
The microcontroller compares the received transmission with a set of permissions previously entered through either the keypad or the embedded web server by the user.
If the permissions are recognized as admissible, the microcontroller will output a signal to the solenoid driver circuit which will engage the solenoids, thus unlocking the door.
Information about system settings can be viewed either on the LCD using the keypad to navigate or by accessing the embedded web server using a PC.

21. PCB Layout Design Considerations Separate digital and analog grounds
Make ground loops as short as possible
Similar circuits were placed closely together for clarity and ease of routing.
Increased trace size for power supplies and larger current supply and ground buses
Decoupling capacitors were used for the larger IC devices such as the microcontroller.

22. PCB Layout

23. PCB Layout Power MOS Circuitry Optoisolators 3.3V Power Regulator
5V Regulator

24. PCB Power Regulators
9.8V Regulator and 15V Regulator

25. Microcontroller

26. PCB Layout
Keypad Encoder

27. PCB Layout
DB9 Connectors at edge of board

28. Software Design/Development Status
On power-up, the microcontroller will enter a startup code section which will initialize the device, performs a debug sequence, set defaults, and load the web server.
Next, it will enter a continuing loop which will poll the possible interrupts of the system: keypad, RF-ID, and Ethernet controller.
When one of these interrupts is asserted, the software will address it accordingly.
Additionally, there will be setup menus for entering permission information and an online engineering mode to check ports, SCI, web server, and other modules.
The software will cause the microcontroller to enter power down mode if an interrupt is not received in a certain time and will be resumed on assertion of aforementioned interrupts.

29. Project Completion Timeline
Week of:
Primary Task
Secondary Task
Oct 10-Oct 16
Design Review Revisions
Preliminary Coding Modules
Oct 17-Oct 23
Code Module Testing
Oct 24-Oct 30
Patent Liability Analysis
Hardware and Software Development
Oct 31-Nov 6
Reliability Analysis
Nov 7-Nov 13
Software Design Considerations, Narrative, and Documentation Report
Preliminary Debugging
Nov 14-Nov 20
Social and Environmental Analysis
Debugging
Nov 21-Nov 27
Debugging and Assembly
User Manual Development
Nov 28-Dec 4
Final Report and Video
Dec 5-Dec 11
Poster and Senior Design Report
Dec 12-Dec 14

30. Questions / Discussion