Here on this page is my second robot Zwobot. Until now I only built the Chassis. Anyway here are a few pictures of it. I found some round turntables in a shop, with a diameter of 25 cm. Because I wanted to build a round robot I decided to take this thing home.


First of all I opend the turntable to get out the balls that kept it turning. Then I cut two pieces out for the wheels. After that I mounted the two RB35 gearmotors.

Attached two wheels on the motors and a third wheel on the back


I glued the wheels to the motors. The glue is strong enough to hold the wheels while drivinng, but you can get them off from the metal.

Added the second floor


For the H-bridge I choosed the SN754410 from TI. I combined it with an IS471F on a little board. It is mounted on the back of the robot so that it´s my back sensor


I bought the batterys, unfortunally I didn´t read the description and thougt it would look like the one on the picture. So I had to move the H-Bridge und the rear sensor is lost so far.

The controller is a 68HC908GP32 as on my first robot. Maybe I´ll take more than one controller for this robot. I made the first test run wit only a few sensors. With the 200 RPM motors it is quite fast. The bottom level is equipped with 5 IS471F infrared sensors. The sensors are connected with a PCF8574 I2C port expansion. The PCF8574 has its own little board which serves power supply for the sensors. Because the MC68HC908P32 has no hardware I2C interface, the interface is emulated in software. The Controller is the master, so there is no problem with bus speed. The C functions are in this source file i2c.c and the header file including the definitons is here i2c.h



The bottom level of Zwobot looks like this now.


The bottom side of the toplevel holds the controllerboard I decided to put the controller for the LCd on the top side. The LCD Controller is connected via SCI to the GP32 board



The LCD is not controlled by an MC68HC908QY1 as I plenned first. I decided to use a MC68HC908JK8 because of its hardware SCI. The Software SCI was slowning the LCD down a little bit. The controller and the LCD went to the top side of the upper platform. You can find the description of Zwobots Display on a seperate page