[mythtv-users] direct usb-usb cable to replace usb-uirt

Dan Wilga mythtv-users2 at dwilga-linux1.amherst.edu
Fri Oct 30 17:16:33 UTC 2009


At 4:08 PM +0100 10/30/09, Marius Schrecker wrote:
>I figured the actual signal would be different from what lirc would 
>transmit, bu tif I plug a UIRT into my Linux box, and cat what comes 
>in over the /dev/ node, I should be able to see what my STB would 
>expect to receive.

No, not likely, IMHO. The UIRT talks to the Linux box using a 
proprietary (but documented) protocol, which encapsulates the IR 
pulses. The STB most likely uses another protocol entirely to talk on 
its USB port. It's very unlikely that it uses a protocol that 
resembles either raw IR pulses or what the UIRT uses.

It's most likely that the STB uses a protocol that says, "tune to 
channel 1-2-3". Contrast that with the USB_UIRT protocol, which says, 
"I got a series of IR pulses in this on-off sequence," or, "I got a 
series of IR pulses that I recognize as this remote control 
keypress." (This latter mode of the UIRT isn't actually used in 
LIRC.) In short, the STB likely talks in channel numbers, whereas the 
UIRT talks in pulses and keypresses. It's apples and oranges.

Try taking your STB's model name/number and Googling it with "USB 
tune" to see what you get. You might be surprised.
-- 
Dan Wilga                                                        "Ook."


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