Remote System Restarter

1. Remote System Restarter ECE 4542-01: Senior Design II Mississippi State University October 4, 2005

2. Presentation Overview • Background Information • Current Status • Design Requirements • Hardware Aspects • Software Aspects • PCB Layout • Where we are headed

3. Remote Control System Access • Access computer from anywhere

4. Uses • File Access • Homework • Personal Files • Server Update • Web Updates • Maintenance • Technical Support • Computer Assistance • Helping a Friend

5. Team Assignments Thomas Brown PIC software Audio Playback PC interface Lindsey Coggin Team Leader PIC software Audio Playback DTMF decoding Ken Bush PCB Layout Testing Bret Birdwell Ring Detection PC interface Hook control Dr. Follett Advisor

6. Accomplishments • The prototype works!!!! • Needs some fine tuning…. • Add more messages for the user • Make DTMF decoder more sensitive to tones • LM386 is too noisy and so is the LM471 op amp

7. Senior Design II Goals • PCI slot • Detect button presses 95% • Understandable audio • Will go to a “locked” state

8. Technical Design Constraints

9. Size

10. Practical Design Constraints

11. Ethical • Password Protection • Consecutive Failure • Device Disables • Must be Manually Reset

12. Hardware Flowchart Telephone Network Ring Detection PIC Hook Control DTMF Decoder PC Interface Audio Playback

13. Ring Detection Microcontroller will need to have ability to count number of rings • Convert 90V AC ring signal to 5V DC pulses • Use input pin on microcontroller for counting pulses

14. Ring Detection • Build or use IC with ring detection? • Decision: Build it!! • ICs would have wasted functionality • Cost

15. Ring Detection Circuit

16. DTMF Decoder • Dual Tone Multifrequency (DTMF) Decoder used to decode button presses of touch-tone keypad • Allows RSR to receive commands from user

17. DTMF Decoder • Used CM8870 DTMF Decoder IC • Four output pins connected as inputs to microcontroller • Output is 4-bit binary number • Cheap

18. Audio Playback • Audio playback needed to play recorded messages to user as instructions • Options: • EEPROM with DAC • Audio Record/Playback IC

19. Problems: • Serial EEPROMs: • Overclocking I2C SCL line • Not enough address pins • Parallel EEPROMs: • Expensive • Would use too many I/O pins on microcontroller

20. ISD5116 • Audio Record/Playback IC • Analog inputs and outputs • Can store analog or digital data • Can store 8 minutes of audio • Controlled via I2C bus

21. Relays • Minimum Requirements: • Coil voltage of 5V • High coil resistance • Current rating of at least 20mA • FCC Part 68 compliant

22. Test Plan • Each part tested independently before added to the rest of the circuit • Ring Detection • Connected to telephone network and called • Check output with oscilloscope • Voltage Regulators • Use oscilloscope to check voltage supplied to circuit • DTMF Decoder • Diodes used at output pins to visually see decoded key press

23. Voltage supply from PC • The voltage supplied from the stand by 5VDC pin of the computer power supply is 5.04V

24. Ring Detection Circuit Output • Output of Ring detection circuit is low while ringing for 2.3 sec and high in between rings for 3.7 sec.

25. Software • Three layers • Top layer: PIC software (FSM) • Finite State Machine controls everything • Middle layer: ISD functions • Invoked by FSM to control audio chip • Bottom layer: I2C functions • Invoked to provide communication between PIC and audio chip

26. Top layer: PIC software (FSM) • The FSM uses the bottom two layers. • FSM implemented using a C switch statement like below: #define firstState = 0; #define secondState =1; unsigned char state: state= firstState; switch(state){ case firstState: // do some operations break; case secondState: // do some operations break; }

27. Top layer: PIC software (FSM) • The FSM makes control of the program very easy. • Our device has 14 states:

28. Middle layer: ISD functions • ISD functions enable audio playback of messages • ISD functions use the bottom layer I2C functions • Playback function: • isd_play_address(unsigned int address); • Stop playback function: • isd_stop( );

29. Bottom layer: I2C functions • Popular communication protocol • Used on the master chip (PIC18) to communicate with: • ISD5116 Audio Chip

30. Testing Software • Thorough testing of the FSM is important. • Hyperterminal is the tool used to do this using printf statements. • monitor current state • monitor what buttons are being pressed • monitor interrupt timer • monitor variable values • A simple example: • printf(“current state = onHook”);pcrlf;

31. Time Line Aug. 18 Sept. 18 Nov. 28 Oct. 18 Nov. 18 Schematic 100 % Initial PCB Layout Finished and In Hand 75% PCB Population Populated Testing DTMF Troubleshooting 85% Audio Troubleshooting 100% PIC Software Testing/Fine Tuning

32. Actual Size Used • 6.6” X 3.5” - Cut off .7” to avoid the PCI slot, we are using wiring harness instead, much easier to use, and no drivers needed.

33. PCB Layout • Using ORCAD to lay out board. • Schematic completed, board lay out 75% complete. • Tentative completion date 7 October • 5 day lead time from ordering, approx. 5 day shipping time. • 10 day total time to receive.

34. Attachment to PC • Using PCI slot face plate • Attaching board via L-Brackets. • Face plate needs 2 slots for phone jacks, 2 holes for switches, and 2 holes for board mounting.

35. Senior Design II Goals • Clear up audio messages as much as possible • Increase DTMF decoder reliability • Make as user friendly as possible • Make a PCB version

36. Acknowledgements • Dr. Randy Follett • Dr. Robert Reese • Dr. James Harden

37. Any Questions?