Sumovore Manual

Step 32 & 33 - The Chip Carrier and 74HCT240: We’re going to install a
20-pin chip carrier first, simply because it’s an ugly mess to desolder a
backwards 74HCT240. Really, you don’t want to do it.
Just like when you installed the chip carrier for the mainboard’s two chips,
you want to mate the position of the carrier’s notch with the notch printed on
the circuit board at position ‘IC5-74HCT240’. Yes, we know it doesn’t say
‘IC5-Chip Carrier’. Don’t be a smarty-pants!
After you’ve finished inserting the carrier, find your 74HCT240, and insert it
into the carrier, matching up the notch in the chip with the notch on the
carrier (this notch-alignment-thing is pretty cool, eh?).
Note: (referring back to step
4/5...) A major reason for
using a chip carrier is so that
you can isolate the chip during
assembly, then press it in right
at the end of the job. If you’ve
had some bad luck lately and
don’t want to risk it, just
install the carrier NOW, and
install the chip near the end of
constructions
The Discrete Brainboard: BEAM robots usually have simple, robust controller systems, and the Sumovore follows this
tradition. Although we’re using a 74HCT240 octal inverting buffer chip in the circuitry, there aren’t any truly radical BEAM-style
or analog concepts behind it, so we refer to this brainboard being “discrete,” as in “composed of many separate pieces.”
Building a sumo robot brain can be done as simple as using three DPDT relays (see the book “Junkbots, Bugbots, and Bots on
Wheels”), but in doing so, there won’t be a very wide scope of behaviors in the sumo robot. On the other hand, we’ve built
over 20 Sumovore prototypes, each time refining what we can do with a simple controller circuit, and indeed, there’s some
subtle elegance to the discrete brainboard, like:
! Deceleration before reversing the gearmotors to keep the sumo plate edge from lifting off the surface
! Opponent sensor false-trigger filtering
! Smooth left / right opponent tracking
! “Sumo-dance” inhibiting (so the Sumovore knows to try something different after 5 seconds of locking up with the
opponent)
! “Edge-charge” inhibiting (so the Sumovore doesn’t repeatedly head-on charge the sumo ring edge)
! Selectable “Line-follower” or “Sumo” mode (so you can use the Sumovore for line-following contests)
! Optional rear-looking sensors (active looking, or passive sensing of opponent’s IR transmissions)
We designed this brainboard to be very robust and straightforward to build and use, so even if you are planning to use a
microprocessors with your Sumovore, you can use the discrete brainboard as a benchmark to compare your microprocessor
brains against. Not sure if there’s a bug in your code or if it’s a hardware problem? Trade out the microprocessor brainboard for
the discrete brainboard and see if the problem goes away. Last minute competition changes mess up your code? You can always
fall back on the discrete brainboard. For these reasons, we encourage you to build this brainboard even if you have every
intention of eventually plopping a microprocessor on your Sumovore.
Step 32: Install Chip
Carrier at ‘IC5’...
Step 33: ...then install 74HCT240
into chip carrier. Or if you’re feeling
unlucky, wait until all soldering is done
The Solarbotics Sumovore
Building the Mainboard Electronics - 9
Steps 32 & 33: Carrier and 74HCT240
Note: If you’re using Hydro-X or similar solder with water-soluable flux, be sure to wash the board off at the end of construction! Failure to
do so will cause erratic behavior in your Sumovore!
Complete carrer & chip installation. Note
the notch position!