Page 40 - Hacking Roomba

Chapter 2 — Interfacing Basics 21

The hardware design of the Roomba itself prevents some other potential hacking ideas. For
example, although the main drive motors are driven by pulse-width modulation (PWM),
allowing for varying speeds, the vacuum motors are not. Thus the ROI has only simple on/off
commands for the vacuum motors.

The ROI Connector

The ROI connector is a Mini DIN 7-pin jack. “DIN” is a standard connector format; “mini” is
a smaller variation of the original DIN format. The Mini DIN standard is incredibly common
in consumer electronics. S-Video cables use a 4-pin Mini DIN connector, and old PC PS/2
keyboard and mouse connecters are 6-pin Mini DIN.
Figure 2-1 shows what the ROI connector looks like on the Roomba, and Table 2-1 lists the
available signals.

7 6 5

4 3

2 1

FIGURE 2-1: Roomba ROI connector Mini DIN
7-pin socket pin-out

Table 2-1 Roomba ROI Connector Signal Names

Pin Name Description
1 Vpwr Roomba battery + (unregulated)
2 Vpwr Roomba battery + (unregulated)
3 RXD 0–5V serial input to Roomba
4 TXD 0–5V serial output from Roomba
5 DD Device detect (active low), used to wake up Roomba from sleep mode
6 GND Roomba battery - (ground)
7 GND Roomba battery - (ground)