Anelok: new circuit revision (20150106)

Werner Almesberger werner at
Tue Jan 6 05:42:29 UTC 2015

I finally sat down and corrected most of the errata from the 20140712
board and also made some small improvements. The highlights:

- the board is now 1 mm wider, to give the FPC on the OLED more room
  for bending,

- the rfkill switch now switches VRF between VSYS and GND instead of
  acting as "syskill" by switching VSYS between VRF and GND,

- removed copper from under the 32.768 kHz crystal, which happens to
  have a keep-out area there (I suspect that having missed this
  requirement is why the crystal on my board #2 doesn't oscillate),

- found a nicer diode to prevent reverse current into VBUS (the one I
  used so far has fairly large leakage, but it's the best I have at
  home), and

- added a small test pad to PTD1. This may become a battery sense
  input in the future. More about this later.

The updated schematics:

The layout:

For comparison, the previous version is here:

I still need to update the BOM. Also, the widening of the PCB still
has to propagate into related material, such as the case design or
the wire frame model with pop-ups.

I don't plan to make any prototypes based on this design myself but
Xiangfu has said he wants to make a few boards.

Note that the widening of the PCB will also allow growing the touch
sensor a little, and I have an idea for growing and at the same time
simplifying it even further. The 20150106 design doesn't have this
change since I still have to make a board (just the sub-board) and
test whether this works as well as I hope.

- Werner

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