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v0.4 Electrical Plan

Parkview785 edited this page Sep 21, 2022 · 10 revisions

TODO before v0.4 order

  • determine why/if battery 5V jump start is needed. Hypothesis: power MOSFET Rds might be too high? Loosing too much voltage across the MOSFET?
  • test and integrate the external PDM microphone board
  • test more GPIOs - LED indicator, capacitive touch

Must Have Changes

Fix bugs from v0.3

  • connect 3.3VA to 3.3V
  • change TP4056 to correct package, or replace it
  • work with mechanical for better mounting holes: Changed holes to M1.6 for screws, and a M1.5 alignment pin hole
  • fix silk screen so all is printed
  • boards sometimes need 5V jumpstart to run off of 3.7V battery

On-board power switch

Switch must stick out the side of the PCB, into the existing slots on the glasses frame, and be flush with the outside case.

Power / Battery Management

We need a more efficient power solution that works to use full capacity of 2x single cell LiPoly batteries. We also need a discharge and charging solution that balances the batteries for safety and longevity. We also want a coloumb counter so we can always know the current charge state of the device.

  • choose battery scheme, charging IC(s), voltage IC, columb IC
  • integrate into board
  • see v0.4 scratchpad wiki page for list of possible chips to incorporate (see link below)

LED indicators

  • choose RGB LEDs: WS2812B-2020
  • work with mechanical to identify placement - on endpiece sensor boards?
  • add connector pads for external LEDs
  • integrate 2+ user-facing RGB LEDs into current design (only one needed)

Heads Up Display

  • add a 3 pin GND, 3V3 100mA, GPIO26 DAC connector to allow experimentation with composite video

Maybe/next version

Add Speakers

  • find smallest speaker we can use with ESP32 (see v0.4 scratchpad wiki page)
  • work with mechanical to get proper positioning
  • integrate into current board

More Microphones

  • select true I2S microphones - see v0.4 scratchpad wiki page: i2S MEMS Microphones
  • change external microphone board to incorporate I2S microphone

Review

  • onboard CH9102 UART - is it working ok?
  • are the test points ok. Footprint ok?
  • chip antenna, acceptable range?