Hacking the Tschibo Vacuum

In the netherlands a lot of webshops have the Tchibo Vacuum robot on on sale at ridiculous discount prices. <30EUR for a robot with two motorized wheels, encoders, bumpers, battery, obstacle sensors, and (best of all) very straightforward electronics! On this forum the message was posted that the Tchibo robot is a Roomba – Original clone, so perhaps this article is of use of Roomba Original owners too. Other great resource is ofcourse the roomba hacking forum

The electronics of the Tchibo consist of an ATmega8 microcontroller running at 8 MHz, with two 74HC245 bus drivers for inputs and an 74HC373 for outputs. Everything runs on 5V. Motors (two for driving, and 3(!) for cleaning) are controlled by respectively an L298 dual bridge driver and a power MOSFET.

At first I was hoping to hack into the original Atmel microcontroller, and use its serial port pins to make a ‘tap’ into the robot. Unfortunately PC0 and PC1 of the controller have been used to control the latch-inputs of the bus drivers. The approach I settled for was to take a different microcontroller (ATmega32) with more IO-pins and use that to take the place of the original ATmega8.

I really like the Arduino standard, so I took this opportunity to make one of my mega32 boards Arduino compatible, in order to have an Arduino Vacuum Robot. This mostly consisted of rewriting the exisiting STK500-compatible bootloader sources in order to work on the mega32. In the next post I will discuss the software and sources.