1. iRobot Create Introduction Assembled from various online resources
mainly slides and pictures from
Rob Kremer and Jamie Snape

2. Anatomy
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3. Anatomy
Bump Sensors
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4. Anatomy
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5. Overview Based on Roomba robotic vacuum cleaner
Programmable with open interface of over 100 commands
32 internal and external sensors including bumpers and infrared
Expansion port to add microcontroller, Bluetooth, and/or additional sensors

6. Programming (Bluetooth)
Send Open Interface commands via a virtual serial port: baud, 8 data bits, 1 stop bit
Linux stty –F /dev/ttyUSB cs8 -cstopb
Receive sensor data back as packets
Using any scripting language (Perl, Python, etc.)
Drive Create forward (OI script):
(Start in safe mode)
(Drive forward 100 mm/s)

7. Modes OFF PASSIVE SAFE  may be recommended FULL
Unresponsive (except START (128))
Can charge
PASSIVE
Sensor status commands
No Actuator commands
SAFE  may be recommended
Actuator commands
But reverts to PASSIVE if moving forward and any cliff sensor is activated; any wheel drop sensor is activated; or the charger is plugged in
No Charging
FULL
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8. Modes OFF PASSIVE SAFE FULL START (128) SAFE (131) FULL (132)
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9. Modes: WAIT A 5th Mode: WAIT
When in WAIT mode the robot does not respond to ANY input.
Goes into WAIT mode for 3 commands (see WAIT slide):
WAIT-DISTANCE
WAIT-ANGLE
WAIT-TIME
WAIT-EVENT
If the robot is prevented, for some reason, from traveling the distance or the angle, it won’t respond to anything (try the undocumented command 7).
Use only in scripts, NOT RECOMMENDED
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10. Programming (Microprocessor)
Command Module plugs into expansion port
8-bit RISC microprocessor (~18 MHz)
Upload C programs that send Open Interface commands and read sensor data
Open source toolkit (Windows/Mac compatible)
Four extra expansion ports to add custom hardware (sensors, LCD display, etc.)

11. Programming (Microprocessor)
Drive Create with specified velocity and radius (C function):
void drive(int16_t velocity, int16_t radius) {
byteTx(CmdDrive);
byteTx((uint8_t)((velocity >> 8) & 0x00FF));
byteTx((uint8_t)(velocity & 0x00FF));
byteTx((uint8_t)((radius >> 8) & 0x00FF));
byteTx((uint8_t)(radius & 0x00FF)); }

12. Actuators: Drive
DRIVE (137 <velocityhigh> <velocitylow> <radiushigh> <radiuslow>)
2 short (16 bit) parameters
Each represented by 2 bytes, high byte first (so a total of 5 bytes for this command)
Parameter 1: velocity in mm/sec
-500 to +500 (-ve means “backwards”)
Parameter 2: curve radius in mm
-2000 to where -ve means clockwise and +ve means counterclockwise
32768 means “go straight”
-1 and +1 mean spin in place clockwise, counterclockwise respectively
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13. Actuators: LEDs
LEDs (139 <Adv&Play> <powerColor> <powerInten>)
Adv&Play:
Bit 1 (=2): Play LED
Bit 3 (=8): Advance LED
PowerColor (0-255):
0=green; 255=red
PowerIntensity (0-255)
0=off; 255=full intensity
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14. Actuators: Send IR SEND-IR (151 <IRbyte>)
Sends a byte using an add-on circuit and a IR LED
Can be received by the omnidirectional IR receiver at the front of the robot
Could be use to transmit short-distance identifiers for each robot
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15. Actuators: Songs Load a song Play a song
140 <song#> <length> {<note> <duration>}*
<song#>: 0-15
<length>: number of notes (1/2 of bytes) (up to 16 notes)
<note>: see table in OI Manual
<duration>: in 1/64 second …
Play a song
141 <song#>
Doesn’t work if a song is already playing
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16. Inputs: Sensors Read Sensors Also a commands for: 142 <packetID>
Packets 0-6 are “packet groups” (eg: 0 is sensors 7-26, which is 26 bytes [some are two-byte returns])
Packets 7-42 are individual sensors
Either numerical values (1 or 2 bytes) or bitmaps
See OI Manual
Also a commands for:
reading a list of sensors (149)
requesting a continuous stream of packet data (148)
pausing/resuming a stream (150)
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17. Sensor Groups Packets
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18. Sensor Single Packets
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19. Scripts Load a script Play a script Show script
152 <length> <opcode>*
<length>: number of bytes in script (up to 100)
<opcode>: OI commands
Play a script
143
No flow control except for WAIT commands (next slide)
Infinite cycle if script ends with 143
Show script
154
Returns the current script
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20. Scripts: Wait Wait time Wait Distance Wait Angle Wait Event
<time> in 1/10 sec (resolution of 15ms)
Wait Distance
156 <disthigh> <distlow>
<dist> distance in mm. +ve=forward, -ve=back
Works for passively rotating the wheels
Wait Angle
157 <anglehigh> <anglelow>
<angle> angle in deg. +ve=counterclockwise, -ve=clockwise
Wait Event
158 <event#>
<event#>: eg: 1=wheel drop (see table in OI Manual, p.16)
Use -ve for inverse of event (eg: -1 wheel drop stops)
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21. Tasks: measuring
You can track the distance traveled by using sensor 19 (distance)
Angle with sensor 20 (angle)
Note: reading these sensors causes them to be reset
Distance (angles) increment for forward (counterclockwise) and decrement for backward (clockwise)
Class iRobotCreate’s regular sensor reading keeps an accumulator for distance and angle
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22. Tasks: Following a wall
You can track along a wall using the wall sensor (sensor 8)
Use Drive straight (137 <velocity> 32687) when the wall is there; or a wide right curve (137 <velocity> -2000) when the wall goes away
You should expect the occasional right-bump
If you get a left-bump, you’ve probably hit a corner
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23. Commands from shell stty -F /dev/ttyUSB0 57600 cs8 –cstopb
echo -e '\0200\0204' | cat > /dev/ttyUSB0 (full mode)
echo -e -n '\0214\0000\0004\0076\0014\0102\0014\0107\0014\0112\0044\r\n' | cat > /dev/ttyUSB0 (defines song)
echo -e -n '\0215\0000\r\n' | cat > /dev/ttyUSB0 (plays song)
echo -e -n '\0200\0203' | cat > /dev/ttyUSB0 (start move)
echo -e -n '\0211\0000\0144\0200\0000' | cat > /dev/ttyUSB0 (go)

24. Further Reading iRobot Create http://www.irobot.com/sp.cfm?pageid=305
Manuals and downloads