I've been trying to get a working stamp in the bits of free time I've had the past week.  Although the design is goofed, I figured I could hack the connections to make the system work.  I think that approach could work, but instead the soldering was the problem.

Progress (kindof?)

Soldering a 256-pin BGA with a syringe of solder paste and a toaster oven is very error prone.  My theory is that, on my first attempt, I did not use enough solder paste on some of the power supply pins.  Due to this, the 3.3v line sat at zero (which was my observation).  For background, the OSD3358 has on-board regulators and power management.  This obviously wasn't working, and since the SoC worked before, and there were no other obvious problems, I must assume one of the pins was not soldered.

The next logical step is to remove the OSD3358 and try again, and for that I needed a heat gun.  Then we face a worse issue: the heat is not distributed evenly, so the fragile balls on the SoC melted (but only the ones on the edges).  For reference, this is like the legs of a typical IC melting, so it is really bad.  Most of the chip seemed salvadgeable, the melted pins weren't needed for my tests, but resoldering the SoC to the stamp did not fix the power supply problem.

Problems Discovered

I think it wasn't for nothing though, I discovered some more problems in the board design, namely that the 5v USB input pin is not connected to any external pin (I had corrected this in my tests), and that the pinout has conflicts.  Of course, there is also the issue mentioned in the previous log file.

Planning a Board Rev, and Other Necessities of this Project

I could try making it work again with a new SoC chip, but I don't think it's worth it.  There's too high a likelyhood of more things going wrong, and I've identified things I can fix for the next board rev.  This design is difficult to get working due to the mentioned issues, it would be a waste of my time to keep trying with the current design.

I will need better and easier ways to test these stamps soon.  I'll probably need some sort of test setup to verify these things work, and I also want to make some cool projects with them.

One project I'm thinking of starting is making a digital notebook with wikipedia downloaded, and an EPaper display + pen.  Perhaps I'll add other utilities like a GPS and compass.  Although things like this exist, I think it would be a nice project, a good way to exercise the BeagleStamp, and it's always nice to have full control of the source code on your devices anyway.

Let me know your thoughts.  Advice for making a test aparatus?  Ideas for this proposed notebook/tablet project?  Advice for soldering BGA packages?