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I'm trying to get the "Torobot" USB servo controller to work with Angstrom Linux on a Beagle Board XM.

The servo controller registers as a USB device. The device just takes simple text commands, but there is no TTY associated with it. So I'm not sure how to send commands to it.

Can I just send data like this (assuming that 002/005 is the device):

$ cat file.txt >> /dev/bus/usb/002/005

Or do I need to associate it with the generic USB device? If so, how do I do that?

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2 Answers 2

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you can pyusb for send data http://pyusb.sourceforge.net/docs/1.0/tutorial.html and your data information is here http://www.torobot.com/down/usc_en.pdf i think you python code like this

    import usb.core
import usb.util

# find our device
dev = usb.core.find(idVendor=0xfffe, idProduct=0x0001)

# was it found?
if dev is None:
    raise ValueError('Device not found')

# set the active configuration. With no arguments, the first
# configuration will be the active one
dev.set_configuration()

# get an endpoint instance
cfg = dev.get_active_configuration()
interface_number = cfg[(0,0)].bInterfaceNumber
alternate_settting = usb.control.get_interface(interface_number)
intf = usb.util.find_descriptor(
    cfg, bInterfaceNumber = interface_number,
    bAlternateSetting = alternate_setting
)

ep = usb.util.find_descriptor(
    intf,
    # match the first OUT endpoint
    custom_match = \
    lambda e: \
        usb.util.endpoint_direction(e.bEndpointAddress) == \
        usb.util.ENDPOINT_OUT
)

assert ep is not None

# write the data
ep.write('#1P1500T100\r\n')
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  • $\begingroup$ cool - I'll have to dust off my (weak) python chops...but will give it a try. Thanks! $\endgroup$
    – ChronoFish
    Aug 29, 2013 at 19:04
  • $\begingroup$ thanks... there a lot of dependencies that don't come on the Angstrom distribution for this. I have filled most of those, but still getting errors. See my latest question: robotics.stackexchange.com/questions/2132/… $\endgroup$
    – ChronoFish
    Dec 7, 2013 at 23:41
  • $\begingroup$ I could not get pyUSB to work - but I did find away to access the board directly through the tty $\endgroup$
    – ChronoFish
    Dec 15, 2013 at 9:24
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Finally Success:

I found that the Torobot USB board could be communicated with an Arduino serial driver. Conveniently this is available through opkg:

opkg install kernel-module-cdc-acm

When the board is plugged in, it comes up as

/dev/ttyACM0

From here you can simply echo commands to the device. 

echo "#8P1500T100" > /dev/ttyACM0

This basically says "set servo 8 to position 1500 with speed 100"

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