Remote System Restarter

1. Remote System Restarter ECE 4542-01: Senior Design II Mississippi State University November 29, 2005

2. Presentation Overview • Background Information • Accomplishments • Design Requirements • Hardware Aspects • Software Aspects • PCB Layout

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. Problem • System Freeze • Power Outage

6. 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

7. Accomplishments • Interface with an answering machine • Answer telephone after set number of rings • Fit into the PCI slot • Land-line button presses – 100% • Cellphone button presses – 100% except for buttons 1,2,3 • Clear and understandable audio • Perform Desired Power option

8. Accomplishments cont.. • Will go into a locked state • Allow user to program 5 digit access code and number of rings to answer • Inform current state of device

9. Technical Design Constraints

10. Practical Design Constraints

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

12. 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

13. Ring Detection • Build or use IC with ring detection? • Decision: Build it!! • ICs would have wasted functionality • ICs also would cost more • We built it at a cost of 2.73 for 1 and 1.30 for 1000 • IC’s start at around 4 dollars

14. Ring Detection Circuit

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

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

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

18. Problems: • Serial EEPROMs: • Overclocking I2C SCL line • Not enough address pins • Parallel EEPROMs: • Expensive ($40 for 1MB) • We would need four 1MB to for 60 sec • Would use too many I/O pins on microcontroller

19. 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

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

21. Test Plan • Each part tested independently before added to the rest of the circuit • Ring Detection • Used PSpice to draw and simulate circuit • 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 • Hyperterminal was also used to see DTMF results

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

23. 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.

24. 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

25. 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; }

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

27. 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( );

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

29. 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;

30. Time Line Aug. 18 Sept. 18 Nov. 28 Oct. 18 Nov. 18 Schematic 100 % Initial PCB Layout Finished and In Hand 100% PCB Population Populated Testing 100% DTMF Troubleshooting 90% Audio Troubleshooting 100% PIC Software Testing/Fine Tuning 100%

31. PCI Standard Sizes

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 • Used ORCAD to lay out board • Two iterations to complete, an initial prototype and a production board

34. PCB Layout

35. Attachment to PC • Using PCI slot face plate • Attached board via L-Brackets. • Face plate has 1 slot for double phone jack, 2 holes for switches, and 2 holes for board mounting.

36. Board Attachments

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

38. Any Questions?