iRobot ROOMBA - SERIAL COMMAND INTERFACE User manual

iRobot®Roomba®
Serial Command Interface
(SCI) Specification
© 2005 iRobot Corporation. All rights reserved. iRobot and Roomba are registered trademarks of iRobot Corporation.
www.irobot.com

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iRobot®Roomba®Serial Command Interface (SCI) Specification
www.irobot.com
SCI Overview
Versions of iRobot®Roomba®Vacuuming Robot manufactured
after October, 2005 contain an electronic and software interface
that allows you to control or modify Roomba’s behavior and
remotely monitor its sensors. This interface is called the iRobot
Roomba Serial Command Interface or Roomba SCI.
Roomba SCI is a serial protocol that allows users to control a
Roomba through its external serial port (Mini-DIN connector).
The SCI includes commands to control all of Roomba’s actuators
(motors, LEDs, and speaker) and also to request sensor data
from all of Roomba’s sensors. Using the SCI, users can add
functionality to the normal Roomba behavior or they can create
completely new operating instructions for Roomba.
Physical Connections
To use the SCI, a processor capable of generating serial
commands such as a PC or a microcontroller must be connected
to the external Mini-DIN connector on Roomba. The Mini-DIN
connector provides two way serial communication at TTL Levels
as well as a Device Detect input line that can be used to wake
Roomba from sleep. The connector also provides an unregulated
direct connection to Roomba’s battery which users can use to
power their SCI applications. The connector is located in the rear
right side of Roomba beneath a snap-away plastic guard.
ROOMBA’S EXTERNAL SERIAL PORT
MINI-DIN CONNECTOR PINOUT
This diagram shows the pin-out of the top view of the female
connector in Roomba. Note that pins 5, 6, and 7 are towards the
outside circumference of Roomba.
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 input (active low) – used to wake up
Roomba from sleep
6 GND Roomba battery ground
7 GND Roomba battery ground
The RXD, TXD, and Device Detect pins use 0 – 5V logic, so
a level shifter such as a MAX232 chip will be needed to
communicate with a Roomba from a PC, which uses rs232
levels.
Serial Port Settings
Baud: 57600 or 19200 (see below)
Data bits: 8
Parity: None
Stop bits: 1
Flow control: None
By default, Roomba communicates at 57600 baud. If you are
using a microcontroller that does not support 57600 baud, there
are two ways to force Roomba to switch to 19200:
METHOD 1:
When manually powering on Roomba, hold down the power
button. After 5 seconds, Roomba will start beeping. After
10 seconds, Roomba will play a tune of descending pitches.
Roomba will now communicate at 19200 baud until the battery
is removed and reinserted (or the battery voltage falls below the
minimum required for processor operation) or the baud rate is
explicitly changed via the SCI.
METHOD 2:
You can use the Device Detect to change Roomba’s baud
rate. After you have awakened Roomba (using Device Detect
or by some other method) wait 2 seconds and then pulse the
Device Detect low three times. Each pulse should last between
50 and 500 milliseconds. Roomba will now communicate at
19200 baud until the battery is removed and reinserted (or the
battery voltage falls below the minimum required for processor
operation) or the baud rate is explicitly changed via the SCI.
Here is a Python code fragment that illustrates this method
(Device Detect is connected to the PC’s RTS line via a level
shifter):
ser = serial.Serial(0, baudrate=19200,
timeout=0.1)
ser.open()
# wake up robot
ser.setRTS (0)
time.sleep (0.1)
ser.setRTS (1)
time.sleep (2)
# pulse device-detect three times
for i in range (3):
ser.setRTS (0)
time.sleep (0.25)
ser.setRTS (1)
time.sleep (0.25)
6
1
3
5
2
4
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iRobot®Roomba®Serial Command Interface (SCI) Specification
www.irobot.com
SCI Modes
The Roomba SCI has four operating modes: off, passive, safe,
and full. On a battery change or other loss of power, the SCI will
be turned off. When it is off, the SCI will listen at the default
baud bps for an SCI Start command. Once it receives the Start
command, the SCI will be enabled in passive mode. In passive
mode, users can do the following:
• Request and receive sensor data using the
Sensors command
• Execute virtual button pushes to start and stop cleaning
cycles (Power, Spot, Clean, and Max commands)
• Define a song (but not play one)
• Set force-seeking-dock mode
Users cannot control any of Roomba’s actuators when in passive
mode, but Roomba will continue to behave normally, including
performing cleaning cycles, charging, etc. When in passive mode,
users can then send the Control command to put the robot into
safe mode.
In safe mode, the users have full control of the robot, except for
the following safety-related conditions:
• Detection of a cliff while moving forward (or moving backward
with a small turning radius)
• Detection of wheel drop (on any wheel)
• Charger plugged in and powered
When one of the conditions listed above occurs, the robot stops
all motors and reverts to passive mode.
For complete control of the robot, users must send the Full
command while in safe mode to put the SCI into full mode. Full
mode shuts off the cliff and wheel-drop safety features. (The
robot will still not run with a powered charger plugged in.) This
mode gives users unrestricted control of the robot’s actuators.
To put the SCI back into safe mode, users can send the Safe
command.
If no commands are sent to the SCI when it is in safe or full
mode, Roomba will wait with all motors off and will not respond
to button presses or other sensor input.
To go back to passive mode from safe or full mode, users can
send any one of the four virtual button commands (Power, Spot,
Clean, or Max). These button commands are equivalent to the
corresponding button press in normal Roomba behavior. For
instance, the Spot command will start a spot cleaning cycle.
Allow 20 milliseconds between sending commands that change
the SCI mode.
Roomba SCI Commands
Listed below are the commands that users send to the SCI over
to the serial port in order to control Roomba. Each command
is specified by a one-byte opcode. Some commands must also
be followed by data bytes. The meaning of the data bytes for
each command are specified with the commands below. The
serial byte sequence for each command is also shown with each
separate byte enclosed in brackets. Roomba will not respond
to any SCI commands when it is asleep. Users can wake up
Roomba by setting the state of the Device Detect pin low for
500ms. The Device Detect line is on Roomba external Mini-DIN
connector.
Start Command opcode: 128 Number of data bytes: 0
Starts the SCI. The Start command must be sent before any
other SCI commands. This command puts the SCI in passive
mode.
Serial sequence: [128]
Baud Command opcode: 129 Number of data bytes: 1
Sets the baud rate in bits per second (bps) at which SCI
commands and data are sent according to the baud code sent
in the data byte. The default baud rate at power up is 57600
bps. (See Serial Port Settings, above.) Once the baud rate is
changed, it will persist until Roomba is power cycled by removing
the battery (or until the battery voltage falls below the minimum
required for processor operation). You must wait 100ms after
sending this command before sending additional commands
at the new baud rate. The SCI must be in passive, safe, or full
mode to accept this command. This command puts the SCI in
passive mode.
Serial sequence: [129] [Baud Code]
Baud data byte 1: Baud Code (0 – 11)
Baud code Baud rate in bps
0 300
1 600
2 1200
3 2400
4 4800
5 9600
6 14400
7 19200
8 28800
9 38400
10 57600
11 115200
Control Command opcode: 130 Number of data bytes: 0
Enables user control of Roomba. This command must be sent
after the start command and before any control commands are
sent to the SCI. The SCI must be in passive mode to accept this
command. This command puts the SCI in safe mode.
Serial sequence: [130]

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iRobot®Roomba®Serial Command Interface (SCI) Specification
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Safe Command opcode: 131 Number of data bytes: 0
This command puts the SCI in safe mode. The SCI must be in
full mode to accept this command.
Note: In order to go from passive mode to safe mode, use the Control
command.
Serial sequence: [131]
Full Command opcode: 132 Number of data bytes: 0
Enables unrestricted control of Roomba through the SCI and
turns off the safety features. The SCI must be in safe mode to
accept this command. This command puts the SCI in full mode.
Serial sequence: [132]
Power Command opcode: 133 Number of data bytes: 0
Puts Roomba to sleep, the same as a normal “power” button
press. The Device Detect line must be held low for 500 ms to
wake up Roomba from sleep. The SCI must be in safe or full
mode to accept this command. This command puts the SCI in
passive mode.
Serial sequence: [133]
Spot Command opcode: 134 Number of data bytes: 0
Starts a spot cleaning cycle, the same as a normal “spot”
button press. The SCI must be in safe or full mode to accept this
command. This command puts the SCI in passive mode.
Serial sequence: [134]
Clean Command opcode: 135 Number of data bytes: 0
Starts a normal cleaning cycle, the same as a normal “clean”
button press. The SCI must be in safe or full mode to accept this
command. This command puts the SCI in passive mode.
Serial sequence: [135]
Max Command opcode: 136 Number of data bytes: 0
Starts a maximum time cleaning cycle, the same as a normal
“max” button press. The SCI must be in safe or full mode to
accept this command. This command puts the SCI in passive
mode.
Serial sequence: [136]
Drive Command opcode: 137 Number of data bytes: 4
Controls Roomba’s drive wheels. The command takes four data
bytes, which are interpreted as two 16 bit signed values using
twos-complement. The first two bytes specify the average velocity
of the drive wheels in millimeters per second (mm/s), with the
high byte sent first. The next two bytes specify the radius, in
millimeters, at which Roomba should turn. The longer radii make
Roomba drive straighter; shorter radii make it turn more. A Drive
command with a positive velocity and a positive radius will make
Roomba drive forward while turning toward the left. A negative
radius will make it turn toward the right. Special cases for the
radius make Roomba turn in place or drive straight, as specified
below. The SCI must be in safe or full mode to accept this
command. This command does change the mode.
Note: The robot system and its environment impose restrictions that may
prevent the robot from accurately carrying out some drive commands. For
example, it may not be possible to drive at full speed in an arc with a large
radius of curvature.
Serial sequence: [137] [Velocity high byte] [Velocity low byte]
[Radius high byte] [Radius low byte]
Drive data bytes 1 and 2: Velocity (-500 – 500 mm/s)
Drive data bytes 3 and 4: Radius (-2000 – 2000 mm)
Special cases: Straight = 32768 = hex 8000
Turn in place clockwise = -1
Turn in place counter-clockwise = 1
Example:
To drive in reverse at a velocity of -200 mm/s while turning at
a radius of 500mm, you would send the serial byte sequence
[137] [255] [56] [1] [244].
Velocity = -200 = hex FF38 = [hex FF] [hex 38] = [255] [56]
Radius = 500 = hex 01F4 = [hex 01] [hex F4] = [1] [244]
Motors Command opcode: 138 Number of data bytes: 1
Controls Roomba’s cleaning motors. The state of each motor is
specified by one bit in the data byte. The SCI must be in safe
or full mode to accept this command. This command does not
change the mode.
Serial sequence: [138] [Motor Bits]
Motors data byte 1: Motor Bits (0 – 7)
0 = off, 1 = on
Bit 7 6 5 4 3 2 1 0
Motor n/a n/a n/a n/a n/a Main
Brush
Vacuum Side Brush
Example:
To turn on only the vacuum motor, send the serial byte
sequence [138] [2].
Leds Command opcode: 139 Number of data bytes: 3
Controls Roomba’s LEDs. The state of each of the spot, clean,
max, and dirt detect LEDs is specified by one bit in the first data
byte. The color of the status LED is specified by two bits in the
first data byte. The power LED is specified by two data bytes, one
for the color and one for the intensity. The SCI must be in safe
or full mode to accept this command. This command does not
change the mode.
Serial sequence: [139] [Led Bits] [Power Color] [Power Intensity]
Leds data byte 1: Led Bits (0 – 63)
Dirt Detect uses a blue LED: 0 = off, 1 = on
Spot, Clean, and Max use green LEDs: 0 = off, 1 = on
Status uses a bicolor (red/green) LED: 00 = off, 01 = red, 10 =
green, 11 = amber
Bit 7 6 5 4 3 2 1 0
LED n/a n/a Status (2 bits) Spot Clean Max Dirt Detect
Power uses a bicolor (red/green) LED whose intensity and color
can be controlled with 8-bit resolution.

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iRobot®Roomba®Serial Command Interface (SCI) Specification
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Leds data byte 2: Power Color (0 – 255)
0 = green, 255 = red. Intermediate values are intermediate
colors.
Leds data byte 3: Power Intensity (0 – 255)
0 = off, 255 = full intensity. Intermediate values are intermediate
intensities.
Example:
To turn on the dirt detect and spot LEDs, make the status
LED red, and to light the power LED green at half intensity,
send the serial byte sequence [139] [25] [0] [128]
Song Command opcode: 140 Number of data bytes:
2N + 2, where N is the
number of notes in the song
Specifies a song to the SCI to be played later. Each song is
associated with a song number which the Play command uses
to select the song to play. Users can specify up to 16 songs
with up to 16 notes per song. Each note is specified by a note
number using MIDI note definitions and a duration specified
in fractions of a second. The number of data bytes varies
depending on the length of the song specified. A one note song
is specified by four data bytes. For each additional note, two data
bytes must be added. The SCI must be in passive, safe, or full
mode to accept this command. This command does not change
the mode.
Serial sequence: [140] [Song Number] [Song Length] [Note
Number 1] [Note Duration 1] [Note Number 2] [Note Duration 2]
etc.
Song data byte 1: Song Number (0 – 15)
Specifies the number of the song being specified. If you send
a second Song command with the same song number, the old
song will be overwritten.
Song data byte 2: Song Length (1 – 16)
Specifies the length of the song in terms of the number of notes.
Song data bytes 3, 5, 7, etc.: Note Number (31 – 127)
Specifies the pitch of the note to be played in terms of the MIDI
note numbering scheme. The lowest note that Roomba can
play is note number 31. See the note number table for specific
notes. Any note number outside of the range of 31 to 127 will
be interpreted as a rest note and no sound will be played during
this note duration.
Song data bytes 4, 6, 8, etc.: Note Duration (0 – 255)
Specifies the duration of the note in increments of 1/64 of a
second. Therefore, half-second long note will have a duration
value of 32.
Note Number Table for Song Command (with Frequency in Hz)
Number Note Frequency
31 G 49.0
32 G# 51.0
33 A 55.0
34 A# 58.3
35 B 61.7
36 C 65.4
37 C# 69.3
38 D 73.4
39 D# 77.8
40 E 82.4
41 F 87.3
42 F# 92.5
43 G 98.0
44 G# 103.8
45 A 110.0
46 A# 116.5
47 B 123.5
48 C 130.8
49 C# 138.6
50 D 146.8
51 D# 155.6
52 E 164.8
53 F 174.6
54 F# 185.0
55 G 196.0
56 G# 207.7
57 A 220.0
58 A# 233.1
59 B 246.9
60 C 261.6
61 C# 277.2
62 D 293.7
63 D# 311.1
64 E 329.6
65 F 349.2
66 F# 370.0
67 G 392.0
68 G# 415.3
69 A 440.0
70 A# 466.2
71 B 493.9
72 C 523.3
73 C# 554.4
74 D 587.3
75 D# 622.3
76 E 659.3
77 F 698.5
78 F# 740.0
79 G 784.0
Number Note Frequency
80 G# 830.6
81 A 880.0
82 A# 932.3
83 B 987.8
84 C 1046.5
85 C# 1108.7
86 D 1174.7
87 D# 1244.5
88 E 1318.5
89 F 1396.9
90 F# 1480.0
91 G 1568.0
92 G# 1661.2
93 A 1760.0
94 A# 1864.7
95 B 1975.5
96 C 2093.0
97 C# 2217.5
98 D 2349.3
99 D# 2489.0
100 E 2637.0
101 F 2793.8
102 F# 2960.0
103 G 3136.0
104 G# 3322.4
105 A 3520.0
106 A# 3729.3
107 B 3951.1
108 C 4186.0
109 C# 4434.9
110 D 4698.6
111 D# 4978.0
112 E 5274.0
113 F 5587.7
114 F# 5919.9
115 G 6271.9
116 G# 6644.9
117 A 7040.0
118 A# 7458.6
119 B 7902.1
120 C 8372.0
121 C# 8869.8
122 D 9397.3
123 D# 9956.1
124 E 10548.1
125 F 11175.3
126 F# 11839.8
127 G 12543.9

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iRobot®Roomba®Serial Command Interface (SCI) Specification
www.irobot.com
Play Command opcode: 141 Number of data bytes: 1
Plays one of 16 songs, as specified by an earlier Song
command. If the requested song has not been specified yet,
the Play command does nothing. The SCI must be in safe or full
mode to accept this command. This command does not change
the mode.
Serial sequence: [141] [Song Number]
Play data byte 1: Song Number (0 – 15)
Specifies the number of the song to be played. This must match
the song number of a song previously specified by a Song
command.
Sensors Command opcode: 142 Number of data bytes: 1
Requests the SCI to send a packet of sensor data bytes. The
user can select one of four different sensor packets. The sensor
data packets are explained in more detail in the next section.
The SCI must be in passive, safe, or full mode to accept this
command. This command does not change the mode.
Serial sequence: [142] [Packet Code]
Sensors data byte 1: Packet Code (0 – 3)
Specifies which of the four sensor data packets should be sent
back by the SCI. A value of 0 specifies a packet with all of the
sensor data. Values of 1 through 3 specify specific subsets of
the sensor data.
Force-Seeking-Dock Command opcode: 143 Number of data bytes: 0
Turns on force-seeking-dock mode, which causes the robot
to immediately attempt to dock during its cleaning cycle if it
encounters the docking beams from the Home Base. (Note,
however, that if the robot was not active in a clean, spot or max
cycle it will not attempt to execute the docking.) Normally the
robot attempts to dock only if the cleaning cycle has completed
or the battery is nearing depletion. This command can be sent
anytime, but the mode will be cancelled if the robot turns off,
begins charging, or is commanded into SCI safe or full modes.
Serial sequence: [143]

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iRobot®Roomba®Serial Command Interface (SCI) Specification
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Roomba SCI Sensor Packets
The robot will send back one of four different sensor data
packets in response to a Sensor command, depending on the
value of the packet code data byte. The data bytes are specified
below in the order in which they will be sent. A packet code value
of 0 sends all of the data bytes. A value of 1 through 3 sends a
subset of the sensor data. Some of the sensor data values are
16 bit values. These values are sent as two bytes, high
byte first.
Sensor Packet Sizes
Packet code Packet Size
0 26 bytes
1 10 bytes
2 6 bytes
3 10 bytes
Bumps Wheeldrops
Packet subset: 1
Range: 0 - 31
Data type: 1 byte, unsigned
The state of the bump (0 = no bump, 1 = bump) and wheeldrop
sensors (0 = wheel up, 1 = wheel dropped) are sent as individual
bits.
Bit 7 6 5 4 3 2 1 0
Sensor n/a n/a n/a Wheeldrop Bump
Caster Left Right Left Right
Note: Some robots do not report the three wheel drops separately. Instead,
if any of the three wheels drops, all three wheel-drop bits will be set. You
can tell which kind of robot you have by examining the serial number
inside the battery compartment. Wheel drops are separate only if there is
an “E” in the serial number.
Wall
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the wall sensor is sent as a 1 bit value (0 = no wall,
1 = wall seen).
Cliff Left
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the cliff sensor on the left side of Roomba is sent
as a 1 bit value (0 = no cliff, 1 = cliff).
Cliff Front Left
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the cliff sensor on the front left side of Roomba is
sent as a 1 bit value (0 = no cliff, 1 = cliff).
Cliff Front Right
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the cliff sensor on the front right side of Roomba is
sent as a 1 bit value (0 = no cliff, 1 = cliff)
Cliff Right
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the cliff sensor on the right side of Roomba is sent
as a 1 bit value (0 = no cliff, 1 = cliff)
Virtual Wall
Packet subset: 1
Range: 0 – 1
Data type: 1 byte, unsigned
The state of the virtual wall detector is sent as a 1 bit value (0 =
no virtual wall detected, 1 = virtual wall detected)
Motor Overcurrents
Packet subset: 1
Range: 0 – 31
The state of the five motors’ overcurrent sensors are sent as
individual bits (0 = no overcurrent, 1 = overcurrent).
Bit 7 6 5 4 3 2 1 0
Motor n/a n/a n/a Drive
Left
Drive
Right
Main
Brush
Vacuum Side
Brush
Dirt Detector Left
Packet subset: 1
Range: 0 - 255
Data type: 1 byte, unsigned
The current dirt detection level of the left side dirt detector
is sent as a one byte value. A value of 0 indicates no dirt is
detected. Higher values indicate higher levels of dirt detected.
Dirt Detector Right
Packet subset: 1
Range: 0 – 255
Data type: 1 byte, unsigned
The current dirt detection level of the right side dirt detector
is sent as a one byte value. A value of 0 indicates no dirt is
detected. Higher values indicate higher levels of dirt detected.
Note: Some robots don’t have a right dirt detector. You can tell by removing
the brushes. The dirt detectors are metallic disks. For robots with no right
dirt detector this byte is always 0.

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iRobot®Roomba®Serial Command Interface (SCI) Specification
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Remote Control Command
Packet subset: 2
Range: 0 – 255 (with some values unused)
Data type: 1 byte, unsigned
The command number of the remote control command currently
being received by Roomba. A value of 255 indicates that no
remote control command is being received. See Roomba remote
control documentation for a description of the command values.
Buttons
Packet subset: 2
Range: 0 – 15
Data type: 1 byte, unsigned
The state of the four Roomba buttons are sent as individual bits
(0 = button not pressed, 1 = button pressed).
Bit76543210
Button n/a n/a n/a n/a Power Spot Clean Max
Distance
Packet subset: 2
Range: -32768 – 32767
Data type: 2 bytes, signed
The distance that Roomba has traveled in millimeters since the
distance it was last requested. This is the same as the sum of
the distance traveled by both wheels divided by two. Positive
values indicate travel in the forward direction; negative in the
reverse direction. If the value is not polled frequently enough, it
will be capped at its minimum or maximum.
Angle
Packet subset: 2
Range: -32768 – 32767
Data type: 2 bytes, signed
The angle that Roomba has turned through since the angle was
last requested. The angle is expressed as the difference in
the distance traveled by Roomba’s two wheels in millimeters,
specifically the right wheel distance minus the left wheel
distance, divided by two. This makes counter-clockwise angles
positive and clockwise angles negative. This can be used to
directly calculate the angle that Roomba has turned through
since the last request. Since the distance between Roomba’s
wheels is 258mm, the equations for calculating the angles in
familiar units are:
Angle in radians = (2 * difference) / 258
Angle in degrees = (360 * difference) / (258 * Pi).
If the value is not polled frequently enough, it will be capped at
its minimum or maximum.
Note: Reported angle and distance may not be accurate. Roomba
measures these by detecting its wheel revolutions. If for example, the
wheels slip on the floor, the reported angle of distance will be greater than
the actual angle or distance.
Charging State
Packet subset: 3
Range: 0 – 5
Data type: 1 byte, unsigned
A code indicating the current charging state of Roomba.
Code Charging State
0 Not Charging
1 Charging Recovery
2 Charging
3 Trickle Charging
4 Waiting
5 Charging Error
Voltage
Packet subset: 3
Range: 0 – 65535
Data type: 2 bytes, unsigned
The voltage of Roomba’s battery in millivolts (mV).
Current
Packet subset: 3
Range: -32768 – 32767
Data type: 2 bytes, signed
The current in milliamps (mA) flowing into or out of Roomba’s
battery. Negative currents indicate current is flowing out of the
battery, as during normal running. Positive currents indicate
current is flowing into the battery, as during charging.
Temperature
Packet subset: 3
Range: -128 – 127
Data type: 1 byte, signed
The temperature of Roomba’s battery in degrees Celsius.
Charge
Packet subset: 3
Range: 0 – 65535
Data type: 2 bytes, unsigned
The current charge of Roomba’s battery in milliamp-hours (mAh).
The charge value decreases as the battery is depleted during
running and increases when the battery is charged.
Capacity
Packet subset: 3
Range: 0 – 65535
Data type: 2 bytes, unsigned
The estimated charge capacity of Roomba’s battery. When the
Charge value reaches the Capacity value, the battery is fully
charged.

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iRobot®Roomba®Serial Command Interface (SCI) Specification
www.irobot.com
Baud data byte 1: Baud Code (0 – 9)
Baud code Baud rate in bps
0 300
1 600
2 1200
3 2400
4 4800
5 9600
6 14400
7 19200
8 28800
9 38400
10 57600
11 115200
Motors data byte 1: Motor Bits
0 = off, 1 = on
Bit 7 6 5 4 3 2 1 0
Motor n/a n/a n/a n/a n/a Main
Brush
Vacuum Side
Brush
Leds data byte 1: Led Bits (0 – 63)
Dirt Detect uses a blue LED: 0 = off, 1 = on
Spot, Clean, and Max use green LEDs: 0 = off, 1 = on
Status uses a bicolor (red/green) LED: 00 = off, 01 = red,
10 = green, 11 = amber
Bit 7 6 5 4 3 2 1 0
LED n/a n/a Status (2 bits) Spot Clean Max Dirt Detect
Power uses a bicolor (red/green) LED whose intensity and color
can be controlled with 8-bit resolution.
Leds data byte 2: Power Color (0 – 255)
0 = green, 255 = red. Intermediate values are intermediate
colors.
Leds data byte 3: Power Intensity (0 – 255)
0 = off, 255 = full intensity. Intermediate values are intermediate
intensities.
Roomba SCI Commands Quick Reference
Command Opcode Data
Byte 1
Data
Byte 2
Data
Byte 3
Data
Byte 4
Etc.
Start 128
Baud 129 Baud
Code
(0 – 11)
Control 130
Safe 131
Full 132
Power 133
Spot 134
Clean 135
Max 136
Drive 137 Velocity
(-500 – 500)
Radius
(-2000 – 2000)
Motors 138 Motor
Bits
(0 – 7)
Leds 139 Led Bits
(0 – 63)
Power
Color
(0 – 255)
Power
Intensity
(0 – 255)
Song 140 Song
Number
(0 – 15)
Song
Length
(0 – 15)
Note
Number
1
(31 – 127)
Note
Duration
1
(0 – 255)
Note
Number
2, etc.
Play 141 Song
Number
(0 – 15)
Sensors 142 Packet
Code
(0 – 3)
Force-
Seeking-
Dock
143

10
iRobot®Roomba®Serial Command Interface (SCI) Specification
www.irobot.com
Roomba SCI Sensors Quick Reference
Packet Code Packet Size
0 26 bytes
1 10 bytes
2 6 bytes
3 10 bytes
Name Groups Bytes Value Range Units
Bumps Wheeldrops 0, 1 1 0 – 31
Wall 0, 1 1 0 – 1
Cliff Left 0, 1 1 0 – 1
Cliff Front Left 0, 1 1 0 – 1
Cliff Front Right 0, 1 1 0 – 1
Cliff Right 0, 1 1 0 – 1
Virtual Wall 0, 1 1 0 – 1
Motor Overcurrents 0, 1 1 0 – 31
Dirt Detector - Left 0, 1 1 0 – 255
Dirt Detector
- Right
0, 1 1 0 – 255
Remote Opcode 0, 2 1 0 – 255
Buttons 0, 2 1 0 – 15
Distance 0, 2 2* -32768 – 32767 mm
Angle 0, 2 2* -32768 – 32767 mm
Charging State 0, 3 1 0 – 5
Voltage 0, 3 2* 0 – 65535 mV
Current 0, 3 2* -32768 – 32767 mA
Temperature 0, 3 1 -128 – 127 degrees C
Charge 0, 3 2* 0 – 65535 mAh
Capacity 0, 3 2* 0 – 65535 mAh
* For 2 byte sensor values, high byte is sent first, followed by low byte.
Bumps Wheeldrops
Bit 7 6 5 4 3 2 1 0
Sensor n/a n/a n/a Wheeldrop Bump
Left
Bump
Right
Caster Left Right
Motor Overcurrents
Bit 7 6 5 4 3 2 1 0
Motor n/a n/a n/a Drive
Left
Drive
Right
Main
Brush
Vacuum Side
Brush
Buttons
Bit 7 6 5 4 3 2 1 0
Button n/a n/a n/a n/a Power Spot Clean Max
Charging State Codes
Code Charging State
0 Not Charging
1 Charging Recovery
2 Charging
3 Trickle Charging
4 Waiting
5 Charging Error
049.05