Re: gEDA-user: Ok, who moved pin 4?

[DJ Delorie <dj@xxxxxxxxxxx>]

> > mini-B connector has an extra pin, and ground is on pin 5 instead of
> > pin 4 like all other USB connectors.
> 
> Ok, now you've got me ohming out my mini-B connectors...

The USB OTG spec says that two mini-B devices can be connected
together.  The *cable* grounds pin 4 on *one* end so that the devices
know who is the initial master.  Since the device only uses that pin
if it supports OTG, and the cable doesn't otherwise connect that pin
to anything else, I got away with just shorting it myself.

> > This board also used the global
> > puller, as I was able to coerce it to give me useful results.
> 
> Do you have pics of that?  I'd like to see what a board meant for the
> global puller comes out looking like.

I created a project page for it:
http://www.delorie.com/electronics/usb-gpio/

> Ok, you've GOT to put up pics of that.

See above.

> Now since you're obviously crazy, it's just a matter of time before
> you email the list with the subject "home hole-wall activation and
> through-hole plating"!

I know of someone who does that.  The technique is straightforward,
but it requires more chemistry than I feel like doing at home.

> [btw, you got me thinking about my current 4 layer board and what it
> would be like to etch at home -- just did a drill report and I have
> 482 15mil vias...]

Mine has 97 holes.  44 were vias.

The through vias aren't that hard; it's the headers that are, or
anything that needs to connect to an inner layer.

For regular through vias, I did this, which was pretty fast:

* Use 13.5 mil holes.  This is the diameter of wire wrap wire.

* Wrap a length of solder around each end of the board, or thread it
  through suitable holes.  The solder acts as a spacer, to keep the
  board up off the table.

* Strip a couple inches of WW wire, flux it, and cut off the stripped
  part.  This is the "raw stock" wire.

* Flux all your via pads, top and bottom.

* For each via, poke the wire through the hole until it hits the
  table.  Solder the top (the wire just stands there, since it's too
  short to cause problems, freeing up your hands).  Flip and make sure
  it actually came through the board; it should extend past the board
  by the thickness of the solder wires.  Cut off the excess on the
  top, repeat.  You get about 10 vias per inch of wire this way.

* Flip the board over and solder all the little bits of wire sticking
  up.  You can bend them over first if you want, but it's not
  required.


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