Subject:
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Re: windows CE
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 3 Mar 1999 22:45:53 GMT
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Original-From:
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rajackson@qnx.+avoidspam+com
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Viewed:
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887 times
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Previously, you (alex wetmore) wrote:
> On Wed, 3 Mar 1999, Joel Shafer wrote:
> > I've thought about porting NQC. I don't think it would be that tough. I
> > think that the main challenge would be to get it to use the CE IR port
> > instead of the IR tower.
>
> There have been a lot of threads on using alternate IR ports, but no one
> has done it successfully (as far as I know). Most computer IR ports
> are IRDA and don't use the same carrier frequencies as the Mindstorms
> stuff. Someone did have a program that would allow some Windows CE
> H/PC devices to send remote IR commands though, and perhaps that could
> be modified to work with the RCX.
My current project (at work) involves both IRDA and IR-remotes. So this
ties in with the RCX stuff to a great extent.
The IRDA standard does not use a carrier frequency. The IR led is pulsed for a
portion of a bit time on a standard serial protocol (start/stop/parity).
The pulsing is used to reduce the power requirements on handheld equipment.
The Mindstorms IR protocol is a serial data stream which is sent over a modulated carrier.
This is simmilar to what is used in TV-remotes as they send a pulse stream
with a modulated carrier. The difference between the the remotes and the
RCX is that the remotes can use pulse, space or shift coded signals where
the RCX uses level coding (mark or space). Also the remotes codelenght can
vary from 1 to 63 bits, the RCX uses 10 bits (1 start, 8 data and 1 stop).
As a side note the 63 bit number may be why most of the learning remotes can
only learn simple messages that are 8 bytes in lenght or less.
Now you could get an IRDA port to simulate the carrier by transmitting
at 38400 and transmitting either an all ones stream or all zeros to rebuild
the serial stream to the RCX. This should work to get a message to the
RCX. The second problem with IRDA is that it has a limited range. It is
designed so that devices on your laptop can communicate so it's normal
working range is in 1-2 meters. The IR led drivers are not designed to
provide the power needed to signal bounce arround the room.
> You can always use the COM port build into your CE device to
> communicate with the RCX. Its not as compact, but it works.
Since IRDA can operate as a simple serial device. It would be simple
to build a IRDA to RS-232 converter (it will need a IR led and Photo
diode and some level shifters). The you could plug the RCX tower into
the converter and the CE device could then signal the tower using it's
IRDA port.
>
> alex
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: windows CE
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| In article <Voyager.99030317455...@qnx.com>, rajackson@qnx.com writes (...) <pedant> 11 bits (1 start, 8 data, 1 odd parity, 1 stop) </pedant> (26 years ago, 4-Mar-99, to lugnet.robotics)
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