Servo - September 2011

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.