trying usb-uirt raw protocol

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Moderator: jrhees

trying usb-uirt raw protocol

Postby jwehle » Tue Aug 24, 2010 9:28 am

It looks to me like lirc 0.8.6 supports the uirt2 and not the usb-uirt.
For example uirt2_send_mode2_raw appears to use the uirt2 protocol
documented at:

rather then the usb-uirt protocol documented at:

and updated by a post at:

Among the differences is how to specify the carrier frequency.

I'm playing with getting lirc to drive the usb-uirt since I recently
purchased one for a project. At the moment I'm attempting to get
the usb-uirt to send KEY_INFO to a Motorola DTA100. I'm using the
config file from:

and executing:

irsend send_once MotorolaDTA100-PaceDC50X KEY_INFO

I'm capturing the result using an IR Widget driving IRScope ...
more information on this device and software is available at:

Straight out of the box, without making any changes, IRScope
shows a signal which isn't close to what the remote generates
(e.g. usb-uirt uses a 10000 Hz carrier, the remote has a 37392 Hz
carrier). After mucking the lirc code IRScope shows a signal
which * is * close to what the remote generated. The problem is
simply that the first two pulses are missing.

The actual conversion with the usb-uirt is:

Code: Select all
  send 23dd

  recv 0905 0101 1a03 04cf

  send 21df

  recv 21

  send 362a 4101 0661 2409 2009 4009 1b09 6a09
       3009 3009 2b09 6509 81f0 0920 0940 091b
       091b 0925 093a 091b 091b 09c0

  recv 20


1) GETVERSION is responding with Protocol Compatibility 1.1.
The document mentioned above is from 2003 and only mentions
Protocol Compatibility 0.0.

a) Is the current protocol documented somewhere?

b) What changed between 0.0 and 1.1?

2) Is there something in GETVERSION which can be used to identify
a UIRT2 from a USB-UIRT 125000 from a USB-UIRT 312500? I'm just
wondering if I can try different baud rates to automatically
identify the UIRT type based on explicit information returning
from GETVERSION, or do I need to guess based on whether at least
a valid response was returned at a particular baud rate.

3) Given the DOTXRAW command I'm sending, any thoughts as to why
I'm loosing the first couple of pulses? The pulses do match
those from the remote with the exception that the first two
are missing ((IRScope shows 18 pulses from the remote and 16
pulses from usb-uirt).

-- John
Posts: 1
Joined: Tue Aug 24, 2010 9:19 am

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