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Open Sesame
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Open Sesame Team• Grant Apodaca
• Team Leader and Bluetooth
• Richie Agpaoa• eCompass and power design
• Evin Sellin• USB and embedded design integration
• Eric Taba• Motor control and mechanical components
• Jeff Bolin• Mobile app, WiFi and web server
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Description
Open Sesame is a portable, affordable, compact and easy-to-use door security accessory, that can unlock your door remotely through WiFi with an android or iOS app, or it can unlock your door through a Bluetooth proximity detector that discriminates between authorized users. It requires a very simple, non-invasive installation, and it is powered from a 9v battery.
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Current Smart Lock MarketAugust Smart Lock
Kwikset Kevo Open Sesame
Bluetooth Yes Yes Yes
WiFi Separate Device No Yes
Platform All* iOS only All
Installation Partial Lock Replacement
Complete Lock Replacement
Uses Existing Hardware
Hands Free iOS only No Yes
Fits all doors No Yes Yes
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Physical Device Design
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PCB Layout - Size● Our prototype is made larger than it needs
to be to ensure success in our design.
● In a consumer design, the processor, wifi, bluetooth, SD card modules could be made smaller with different package types, like BGA.
o Analog power regulation could be done off the board to free up space
o Packages could be placed on the bottom of the plane.
o More than 4 planes could be used for routing.
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Top Level Block Diagram
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Bluetooth● Part used: RN42XV
● Allows device to be activated in close quarters, regardless of internet connectivity
● Device can be set such that it locks and unlocks automatically when bluetooth presence is detected
● Supports secure simple pairing
● Low power sleep mode
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Application• Main user interface
• Includes controls, settings, and automatic status updates
• Multi platform• Android, iOS, Windows
Smartphone, etc…
• Server communication• Used for authentication
and broadcasting/ receiving updates
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Gear Assembly
Specialized Bevel Gear● Designed with screw-holes
for mounting plate and slots for crank
● 5 to 1 Gear Ratio
● Using Inventor 2015, force simulations proved required torque wouldn’t damage gears with iron material
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Motor Control● Motor driven by dual H Bridge chip
● Bipolar hybrid stepper motor operates bolt, locking and unlocking door
● Full-Step Motion: lower power consumption
o Step Resolution: 1.8° - 200 steps
● Quadrature encoder provides feedback on the position of the motor axle
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E-Compass● Part used: LSM303D
● A digital 3-axis accelerometer and 3-axis magnetometer in a single package.
● Used to determine if the door is open, closed, or ajar
● Calibrated such that the magnetic field generated by the motor do not cause distorted measurements
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Power Distribution
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USB and Non-Volatile Memory
SD●Originally SD card was to be used for memory expansion●Eventually was exchanged for USB
USB Flash●Opens possibility for future integration of peripherals such as cameras, or other sensors.
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Challenges Faced● PCB Design Validation
o Grounding plane issue
o Respin process
● Mechanical limitations
o 3D printing flaws
● Bluetooth proximity
o Standardizing distance measurements using bluetoooth connectivity
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Future Improvements
● Camera/Video integrationo Ability to see who’s knocking at the door
● GPS-based proximity detection● Battery monitor● Smaller size
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Sage Advice
● Get started early! ● Plan ahead, include redundant paths● Include as many test pins as possible● Pin out as many GPIOs as possible● Use debugging tools● Listen to Professor Johnson!!!
o Seriously though
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Special Thanks● John Johnson● Wei Dai● Ilan Ben-Yaacov and
Vincent Radzicki● NXP SemiConductors● SunStone Circuits● Rapid Prototypes● The ECE Shop● Department of
Mechanical Engineering● Aubrey Shanahan
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Thank You!
Questions?Comments?Concerns?
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