Setting Up; Jumper Settings - David Griffith P112 Assembly And Operation Manual

4

Setting Up

If you haven't yet washed the board with flux solvent, do so now. That flux goo
isn't just ugly, but it can corrode circuits if left there. This is especially true if
you used paste flux.
Take a break. It's best if you continue tomorrow. Don't let yourself get too
anxious to get this board running. Rest your mind and body and you'll be less
likely to do something stupid later on.
With the board assembled, basic tests may begin with the "obvious" checks for
Vdd-Ground shorts, etc.
Connect power to the board using the provided power pigtail. Red is positive.
Black is ground. Green is reset. Ground that wire and the board will do a
warm restart. Turn the power on and let it sit there for a couple minutes. If
anything smokes or makes a bad smell, go back and check polarities, especially
the tantalum capacitors.
Install the two SRAM chips in U2 and U3, and the flash ROM in U4. This kit
comes with 28-pin parts. The sockets are 32-pin to allow one to install larger
SRAMs and ROMs. Make sure you install these chips with their bottom ends
flush with the bottom ends of the sockets. If mounted with their tops flush, you
probably won't let out the Magic Smoke, but it definitely will not work correctly,
if at all.
Install the rest of the chips and insert the lithium battery into its holder. Pay
close attention to the alignment notches. Chips mounted backwards will usually
get very hot and fail.
4.1

Jumper Settings

The jumper settings shown in the drawing below are for the default configuration
with 64kB RAM installed. Initially, it is recommended that jumper P11 be left
off so that the battery is isolated. This jumper is required when the real-time
clock chip and NVRAM is in use (which is most of the time). The jumper may
be removed in order to blank the NVRAM contents. If the P112 board will be
unused for a long period of time, the battery itself should be removed to avoid
the possibility of leakage. See section 9 for alternative jumper settings and their
purposes.
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