NOTES.txt

###Fri 25 Nov 2016 04:06:11 PM PST
    - For a rechargable option:
       - LiFePO4 18350 sized battery
       - bq25070 ($2.46) or ADP5063 ($3.43) charger
       - MIC5528 ($0.19) or AP7365 ($0.40) 3.3v linear regulator
       - Use battery holder with lugs or wires
       - The chargers can yield a battery output voltage 4.9v, or
         possibly higher. So a regulator is needed.
       - Watch for quiesent currents (which are similar to the ESP8266!)

    - The TLPHnode board should be minimized to reduce cost. Use wires
      to the power source which could be 2 Alkaline AA, or a single
      LiFePO4.

    - The charging circuit could be on the PCB but not populated.

    - The linear regulator could be used to provide a USB powered
      option with the AA batteries as backup.
      

###Sun 27 Nov 2016 11:38:00 AM PST
    - Use a 6 pin connector and ribbon so that the prgm switch can be
      moved to the 'programming' board.
    - Use a LDO linear regulator on the sensor board to protect from
      over voltage of LiFePO4, or even LiPoly, batteries.
    - Put the battery charger IC on the programming board or a separate
      battery supply board.
    - The 'programming' board can be fab as part of the sensor board.
      Use holes or a cutout to make it easier to separate the board.


###Mon 05 Dec 2016 11:53:34 AM PST
    - ST Micro is not forthcoming on the adjustable regulator. So try
      the fixed, even though it is small. Consider laying out a foot
      print for an alternative regulator in addition to the ST Micro.
      I'm not ready to give up on the ST Micro regulator because it has
      such a log quesent current.
      
    TODO:
      - fix alignment between ESP-12 model and ESP-12E footprint - DONE
      - Change pin numbering on ESP-12E footprint to match ESP-12 - DONE
      - change to ESP-12
      - Re-organize footprints - DONE
      - Add 3d models
            - Regulator - flipchip-4
            - RPC connector
            - Switch
            
      - Settle on FPC connector (datasheet is wrong)
      - Update BOM at Digikey
      - 


###Tue 06 Dec 2016 10:00:03 AM PST
    - In order to use a 4 layer board for less than the cost of the last
      board, the area must be less than 1.42 square inches.
    - Keep in mind that a 2 layer board is still 1/2 of that price, but
      the there are other advantages including smaller traces, drills
      and annual rings.

    LIBRARIES
    ---------
    KiCAD has three collections that could be described as libraries:
        - schematic symbols (typically in a library/ directory)
        - 3d models (typically in a modules/packages3d/ directory)
        - footprints
          These are the tough ones to keep straight.
            - The new 'footprint collection structure' is a directory of
              directories.
            - Each sub-directory ends in .pretty.
            - Actual footprints are in individual files beneath the
              *.pretty/ directories.
            - Each *.pretty directory must be added as a separate path.
            - Each *.pretty directory is an individual git repository.
            - There is not clear parent directory name, though in
              ~/kicad/README.md I proposed putting them in the modules/
              directory with the 3d-models

###Thu 08 Dec 2016 09:47:13 PM PST
    - The LPS25HB (pressure sensor) can not be used on an OSH 2 layer
      board because there is not enough clearance between the corner
      pins. The error is 0.3 mils.
    - Set the default design rules as close to the 2 layer as possible,
      while allowing the LPS25HB to be used.


###Mon 12 Dec 2016 02:35:20 PM PST
    - Changed to 6-pin FPC connnector and 2-pin through-hole connector
      for power.