Page 438 - Hacking Roomba

Appendix C — iRobot Roomba Open Interface (ROI) Specification 419

iRobot® Roomba® Open Interface (ROI) Specification
Roomba Open Interface Modes Roomba Open Interface Commands
Listed below are the commands that users send to the ROI over
The Roomba ROI has four operating modes: off, passive, safe,
and full. On a battery change or other loss of power, the ROI will to the serial port in order to control Roomba. Each command
be turned off. When it is off, the ROI will listen at the default is specified by a one-byte opcode. Some commands must also
baud bps for an ROI Start command. Once it receives the Start be followed by data bytes. The meaning of the data bytes for
command, the ROI will be enabled in passive mode. In passive each command are specified with the commands below. The
mode, users can do the following: serial byte sequence for each command is also shown with each
separate byte enclosed in brackets. Roomba will not respond
• Request and receive sensor data using the to any ROI commands when it is asleep. Users can wake up
Sensors command Roomba by setting the state of the Device Detect pin low for
• Execute virtual button pushes to start and stop cleaning 500ms. The Device Detect line is on Roomba external Mini-DIN
cycles (Power, Spot, Clean, and Max commands) connector.
• Define a song (but not play one)
• Set force-seeking-dock mode Start Command opcode: 128 Number of data bytes: 0
Starts the ROI. The Start command must be sent before any
Users cannot control any of Roomba’s actuators when in passive
mode, but Roomba will continue to behave normally, including other ROI commands. This command puts the ROI in passive
performing cleaning cycles, charging, etc. When in passive mode, mode.
users can then send the Control command to put the robot into Serial sequence: [128]
safe mode.
Baud Command opcode: 129 Number of data bytes: 1
In safe mode, the users have full control of the robot, except for
the following safety-related conditions: Sets the baud rate in bits per second (bps) at which ROI
• Detection of a cliff while moving forward (or moving backward commands and data are sent according to the baud code sent
with a small turning radius) in the data byte. The default baud rate at power up is 57600
bps. (See Serial Port Settings, above.) Once the baud rate is
• Detection of wheel drop (on any wheel)
changed, it will persist until Roomba is power cycled by removing
• Charger plugged in and powered the battery (or until the battery voltage falls below the minimum
required for processor operation). You must wait 100ms after
When one of the conditions listed above occurs, the robot stops sending this command before sending additional commands
all motors and reverts to passive mode.
at the new baud rate. The ROI must be in passive, safe, or full
mode to accept this command. This command puts the ROI in
For complete control of the robot, users must send the Full
command while in safe mode to put the ROI into full mode. Full passive mode.
mode shuts off the cliff and wheel-drop safety features. (The Serial sequence: [129] [Baud Code]
robot will still not run with a powered charger plugged in.) This Baud data byte 1: Baud Code (0 – 11)
mode gives users unrestricted control of the robot’s actuators.
To put the ROI back into safe mode, users can send the Safe Baud code Baud rate in bps
command. 0 300
1 600
If no commands are sent to the ROI when it is in safe or full
2 1200
mode, Roomba will wait with all motors off and will not respond
3 2400
to button presses or other sensor input.
4 4800
To go back to passive mode from safe or full mode, users can 5 9600
send any one of the four virtual button commands (Power, Spot, 6 14400
Clean, or Max). These button commands are equivalent to the 7 19200
corresponding button press in normal Roomba behavior. For
8 28800
instance, the Spot command will start a spot cleaning cycle.
9 38400
10 57600
Allow 20 milliseconds between sending commands that change
the ROI mode. 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 ROI. The ROI must be in passive mode to accept this
command. This command puts the ROI in safe mode.
Serial sequence: [130]
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