USB interface protocol for OWI Robotic Arm Edge for MAC

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USB protocol for communicating with OWI robotic arm
USB protocol for communicating with OWI robotic arm

Thanks to this site for publishing the basic protocol. You can get sample code there as well for Linux – Mac.

You can use USB interface module to connect it to PC. Unfortunately official software works only under Windows and do not provide API. I have been able to reverse engineer their USB protocol and write sample code which allows to control the arm from Mac and Linux.

This is USB device with vendor id 0x1267 and product id 0. The device is controlled by 3 byte commands sent via USB control transfers. Command format is byte0, byte1, byte2. Each byte controls a group of arm features. All motors could be controlled independently. Most commands start action which is continued until next action is signalled. Byte ’00’ universally used as stop action.

Bit numbering in byte:

7 (most significant) 6 5 4 3 2 1 0 (least significant)

Meaning of bits in each byte:

Byte 0

First byte controls grip, shoulder and wrist. Bits are assigned as following:

Bit numbers Controls Bit combinations
0,1 Grip 00-do not move, 01-close, 10-open
2,3 Wrist 00-do not move, 01-move up, 10-move down
4,5 Elbow 00-do not move, 01-move up, 10-move down
6,7 Shoulder 00-do not move, 01-move up, 10-move down

Sample commands, activating single motor:

Byte 0 Command
00 stop grip, wrist, elbow and shoulder movement
01 grip close
02 grip open
04 wrist up
08 wrist down
10 elbow up
20 elbow down
40 shoulder up
80 shoulder down

Sample commands activating 2 motors simultaneously:

Byte 0 Command
11 grip close and elbow up
82 grip open and shoulder down

Byte1

Second byte controls base.
Bits are assigned as following:

Bit numbers Controls Bit combinations
0,1 Base 00-do not move, 01-rotate clockwise, 10-rotate counter-clocwise

Sample commands:

Byte 1 Command
00 stop base rotation
01 rotate base clockwise
02 rotate base counter-clocwise

Byte 2

Third byte controls LED light inside the grip.
Bits are assigned as following:

Bit numbers Controls Bit combinations
0 LED 0-off, 1-on

Sample commands:

Byte 2 Command
00 LED off
01 LED on