1. ECE 477 Group 11 • RevGeo • Multipurpose Puzzle Box • Dan Chambers, Jeff King, Josh Marchi, Paul Rosenberger,

2. Abstract • The “Reverse Geocache” Box is a locked box that will only open after one or more pre-determined GPS locations have been visited directing the user to next location by an LCD display. The route is stored on a microSDcard located inside the boxwhich is programmed on a PC. A RFID backdoor will allow for access to box without finishing puzzle.

4. Schematic

5. Preliminary Layout - Autorouter Li-Ion Battery Locking Mechanism - Servo

6. General Layout Considerations • Keep RS232 close to USB port • microSD card should be accessible • USB port accessible to outside of box • Compass should not be placed closed to any EMI producing components as it relies on the earths magnetic field for its accuracy • Headers for most micro pins • Separate circuit into blocks • No analog signals present (only digital) • Trace size for power and gnd: >30mil

7. Power Supply Considerations • Inductor close to switching inputs (short traces) • High Frequency Signal • Decoupling capacitors located close to input pins and gnd • Reduces supply ripple • Provides instantaneous current • Ground plane underneath switching regulator • Minimize noise • Trace Size: 8 mil • Large Inductor placement • Vias placed underneath thermal pad • Thermal performance

8. Power Supply Layout

9. Microcontroller Considerations • Decoupling capacitors (0.1u) placed close to supply pins • Trace length; less than 0.25in • 0.01uF cap in parallel with decoupling caps to filter high freq noise • No external oscillator (Internal 16Mhz Oscillator) • Locate near center of board • Surround components around it • No special trace width required

10. Questions?