- Beta testing has uncovered a couple of needed changes so far:
R2 - should be 3k or less, not 10k. This fixes problems with access to the
configuration program, as well as problems sending waypoints to certain GPS
X3 pin 1 - this was left connected to the 1-wire bus as a throwback to a
previous layout and shouldn't have been included. If you're running more
than 5 volts out (as selected by JP4) and you connect a null modem cable
with pins 1 and 4 connected, you can destroy the processor! The safest way
to prevent this is to cut the trace.
Looking at the top side of the board, find R5 (to the upper right of U2).
There's a via (small plated-through hole) to the left - this is the trace
you want. Cut it anywhere between that via and connector X3. You can use
the housing of X3 as a guide for a blade, and there's little risk of cutting
anything else at that point. Check to make sure there's no continuity
between X3 pin 1 and the via when you're done.
If you do manage to kill the processor thanks to this error, you'll know it
because the processor and U4 will both get warm to the touch. If that
happens, let me know and I'll ship you a new chip.
I've made a couple of changes to the board layout for the next revision, but
they're mostly cosmetic - silkscreen changes, and a couple of parts near U1
reoriented for clarity. I'm going to try to get some other features ready
for testing soon, like the 1-wire bus and power switch, and possibly the
Sorry for the trouble, but this is exactly why it's still in beta! I
appreciate all of the torture testing, deliberate or not. =]