Page 57 - Hacking Roomba

38 Part I — Interfacing

packet group. Perhaps the two most useful values in the power sensors packet for hacking are the
battery current and battery charge. By observing the current you can tell how much power the
project is consuming when it does different things. By watching the charge level you can tell
when Roomba is almost out of juice and needs to be recharged.

byte 16 7 6 5 4 3 2 1 0
charging values: 0:not charging, 1:charging recovery, 2:charging,
state 3:trickle charging, 4:waiting, 5:charging error
byte 17 7 6 5 4 3 2 1 0
battery
voltage range 0 to 65535 mV
(high byte)
byte 18 7 6 5 4 3 2 1 0
battery
voltage range 0 to 65535 mV
(low byte)
byte 19 7 6 5 4 3 2 1 0
battery
current range -32768 to 32767 mA
(high byte)
byte 20 7 6 5 4 3 2 1 0
battery

current range -32768 to 32767 mA
(high byte)
byte 21 7 6 5 4 3 2 1 0
battery
temp- range -128 to 127 degrees Celsius
erature
byte 22 7 6 5 4 3 2 1 0
battery
charge range 0 to 65535 mAh
(high byte)
byte 23 7 6 5 4 3 2 1 0
battery
charge range 0 to 65535 mAh
(low byte)
byte 24 7 6 5 4 3 2 1 0
battery
capacity range 0 to 65535 mAh
(high byte)
byte 25 7 6 5 4 3 2 1 0
battery
capacity range 0 to 65535 mAh
(low byte)
FIGURE 2-7: ROI sensor packet group 3, power and charging sensors