Page 39 - Hacking Roomba

20 Part I — Interfacing

Dirt sensors (left, right)
Wheel drop sensors (left, right, caster)

Button press sensors (power, spot, clean, max)
Infrared sensor (virtual wall, home base, and remote control functions)

Control

The Roomba also contains several actuators and annunciators that can be controlled through
the ROI:

Drive-wheel motors
Vacuum motor
Main brush motor
Side brush motor

Status LEDs
Piezoelectric beeper

Internal State

Additionally, the ROI makes available certain internal states of Roomba:

Battery state and charge level
Motor over-current
Distance traveled
Angle turned

What You Cannot Do
The ROI is simply an interface into the existing microcontroller program running in the
Roomba. It doesn’t bypass it. You cannot get direct access to the Roomba hardware. In general
this isn’t a bad thing. Some of the sensor data is constructed or massaged by this program to be
easier to use. For example, the infrared detector on the top of the Roomba is a single sensor
that responds to the virtual wall unit and remote control, but the ROI provides different sensor
values for those functions. Roomba is parsing the infrared bit stream emitted by those devices
and presenting the result as multiple binary values. It is not possible to parse custom infrared
bit streams, so detecting commands from other remote controls cannot be done. Most disap-
pointingly, it doesn’t provide a sensor interface to the charging dock beacon of the home base
beyond telling Roomba to go into “force-seeking dock” mode.
Beyond access to those data massaging routines, the ROI doesn’t provide any access to the vari-
ous cleaning algorithms used by the Roomba. But that doesn’t mean new ones can’t be created
and commanded through the ROI.