Subsystem Build & Test
Team Vision for Subsystem Level Build & Test Phase
- Changed plan to use pre-made enclosure instead of 3D printing custom enclosure
- Ordered & received enclosure; cut openings for power and communication
- Began design process for brackets to support components inside enclosure
- Re-ran Heat Test with updated components
- Redesigned Interface Module with correct components (prior simulations used components that were not suitable for real-world conditions of this application)
- Created prototype Interface Module on proto board
- Tested prototype Interface Module to verify functionality
- Ordered all electronic components needed for Interface Module
- Discovered new SBC was released over summer, decided to switch to Raspberry Pi 4 (as it offers two video outputs and eliminates video adapter used with old SBC model)
- Discovered Flip Phone running Android OS, which will allow us to use same software as on the touchscreen smartphone. This still needs to be ordered.
- Continued development of software on SBC (for GUI, audio mixing)
- Messaging app allows for the transfer of messaging over bluetooth.
- Calling app has dialing functionality and only allows the user to dial 911.
- Travel case needs to be ordered
- Serial communication between SBC and smartphone must be tested
- Bluetooth audio transfer must be developed and tested
- Android flip phone needs to be ordered
Updated Interface Module Schematics:
Updated Enclosure Design Drawings:
Interface Board Development
NOTE: The interface board must not exceed the following power requirements as dictated by the SBC pins:
- Should not exceed 10mA to drive all transistors, etc. coming from pin 13 (control signal from SBC to interface board to pick up phone)
- Should not exceed 35mA to power all other components coming from pin 17 (3.3v header)
Updated Heat Test
- Test was run for 22 hours in room with ambient temp 73-38 degrees over course of test
- Contents included anker power supply (with ipod touch, tablet, phone charger and SBC connected to simulate loads), line simulator + transformer, SBC with a separate USB power brick just for it,
SBC Software Design Update:
- Software can now identify connected audio devices (both inputs and outputs). Mapping process has been started so that devices can be mapped by the instructor as "instructor headset", "landline phone", "smartphone", etc. Sample audio files can be played to an output.
- GPIO functionality is complete-- can detect input signal from interface module, and can send command to pick up the phone
- GUI development is in progress
- Little progress has been made on bluetooth functionality; that is main focus for next period (in addition to wrapping up other steps)
App Development Screenshots
Risk and Problem Tracking
Functional Demo Materials
Plans for next phase
- Work with Elijah to test serial communication over bluetooth
- Develop serial command set and communication structure/process
- Test audio between phone and SBC over bluetooth
- Continue working with Zhung to test new proto interface board.
- Continue to update and organize the BOM and budget.
- Continue to work with Grace to come up with ways to maximize space inside the electronic enclosure.
- Identify source of humming in interface board circuit
- Modify interface board circuit as necessary to eliminate humming
- Order PCB once humming has been eliminated from circuit design
- By next design review, apps should have full functionality over bluetooth (texting, calling)
- Cut new base plate for inside enclosure (Alex cracked the old one, but we have plenty of spare material)
- continue prototyping brackets for Anker Power Supply and Line Simulator
- print final support brackets (+ spares) for power supply & line simulator