FIGURE 2. Robbie with whiskers.
www.servomagazine.com/index.php?/magazine/article/september2011_Henning
used to do other processing. For best
results, the whole event loop of a
program should complete in just over 20
ms, as otherwise the servos won’t be
updated frequently enough. I love
tinkering with my Boe-Bots. They are a
great platform for experimenting with
robotics. However, I hankered for more
sensors, more processing power, and
longer battery life – basically more
capabilities to explore robotics with.
Before I start describing my hack,
Figure 2 is a photo of “Robbie” equipped
with only whiskers and a piezoelectric
speaker. You can compare it later with
upgraded shots.
Parallax Upgrades for Boe-Bot
There are some easy upgrades for the Boe-Bot
straight from Parallax:
1) BS2p24 with ~3x speed and 8x the program
memory of the BS2, 128 scratchpad variables and 19
more PBASIC commands. There is also the BS2px for
about 50% more speed than the BS2p24. Watch out for
changes in RCTIME, PULSIN, and PULSOUT.
2) The Boe-Boost module
adds a fifth AA cell, boosting the
voltage of the power supply from
6V to 7.5V if you are using
alkaline batteries. You can boost
the voltage from 4.8V to 6V if
you are trying to use Ni-MH
batteries.
3) A Ping))) sensor and
bracket provide a way for Boe-Bot
to tell how far it is from the
nearest object in line with the
direction the Ping))) sensor is
pointing. The Ping))) sensor is
often mounted on a standard
servo, so it can sweep side to
side, thus find any objects in a
180° arc in front of the Boe-Bot
at distances up to three meters
away.
I must admit that the BS2p24 quickly found a home
on Robbie. I couldn’t resist three times the speed and
eight times as much space for programs and 128
scratchpad variables. The extra PBASIC 2. 5 commands
didn’t hurt, either.
Unfortunately for my wallet, that processor upgrade
was only a stop-gap measure, as I really wanted a LOT
longer battery life, more processing power, more memory,
and an ADC with multiple input channels for Robbie.
FIGURE 3. BS2p24 BASIC Stamp
on the Board of Education.
SERVO 09.2011 49