[mythtv-users] Using USB to change channels on cable box?

Bruce Markey bjm at lvcm.com
Thu Aug 16 00:42:22 UTC 2007

Bill Williamson wrote:
> On 8/16/07, Bruce Markey <bjm at lvcm.com> wrote:
>> Christopher Robbins wrote:
>>> I've got a Scientific Atlanta 3250 (non-HD) cable box...It's got a
>>> USB port or two.  Is there any way to control the box via USB?  I've
>> There is one USB port on the front that does recognize numbers,
>> Enter and ESC from a USB keyboard. If you plug a keyboard in
>> you will see that you can change channels with it although I
>> don't know if it supports any other remote control keys. So,
>> it could be used but I don't know if a USB crossover cable or
>> serial to USB or whatever could be connected and I don't know
>> if any software exists that could send keycodes out to a remote
>> USB device. If you come up with a solution, post it here.
> USB is a host/device arrangement, unlike firewire.  A simple crossover
> cable would not work.  (this is also why you cannot "share" a usb
> printer with 2 computers using a usb "hub").
> You'd need to build a device that had 2 USB "devices".  One plugs into
> the myth, one into the cable box, and then you have somesmall chip to
> do commands.

Despite your confidence in your assumptions, USB crossover
cables do exist, usually advertised for Mac to PC or PC to PC
file transfer. These usually have two standard connectors with
some sort of dongle at one end or in the middle. For example:


I'll not argue the point 'cause I don't give a crap but the other
issue is that even if the hardware device could be detected, I
doubt there is any existing software that which sends keystrokes
to impersonate a USB keyboard.

Something like this http://www.usbgear.com/usa/item_288.html
might stand a better chance for LIRC to send fake keyboard
commands out a serial port but I don't give a crap about this

However, I suspect that many brands of cable boxes have USB
ports that would recognize numbers from standard USB keyboards.
If somebody did work out a solution, it may prove to be a generic,
reliable hard-wired solution for several brands of STBs.

--  bjm

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