Hey everybody! I got the PyPPM v2r1 board assembled over the weekend, check it out...
Of course, I ran into several issues. For you schadenfreude enthusiasts, here's a quick rundown:
- Incorrect -2.5V regulator pinout: I had failed to notice that, while the LT1761-5 and LT1761-SD have the same pinout, the LT1964-5 and LT1964-SD don't.
- Swapped feedback resistors on high-current -5.0V rail: I chased my tail for an hour trying to figure out why I was getting -1.5V from the regulator. Turns out I had the feedback network backwards.
- ID10T: I managed to short the +5.0V high-current rail to ground with a bit of stray solder across a bypass capacitor, and ended up releasing magic smoke from an LT3015, several tantalums, a FAN3111 and two diodes. Good grief...
The good news is that everything has been fixed in the schematic and board layout, and the changes are already pushed to GitHub. :) However, I will need to perform some ugly solder hackery to resolve the footprint issue on the LT1964.
To make things even more interesting, the firmware I had prepared for the PyPPMv2 didn't even set up USB communication; the two AVR's are just different enough that I'll need to spend considerable time rewriting the new firmware.
Long story short, while work on the PyPPM project will live on in PyPPMv2, I'm calling PyPPMv1 a finished project, really just for closure's sake. :P PyPPMv2 brings several new and exciting features to the table, but if you're looking for a basic, working Proton Precession Magnetometer, PyPPMv1 is a perfect fit!