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vrf Manchester Code

Question asked by VRFuser on Apr 6, 2006

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> Isn't manchester encoding a fundamental way of transporting bits under
> a clock system

Yes - though I gather that compression is definitely not in the deal.

I'm just wondering how the signal is getting into the system.

Since clocking is important you run into the same problem when trying to use Windows as a function generator - it ain't deterministic. 64ms. is probably doable though. It looks like the encoding isn't all that picky. Still, hardware is much more preferable than software.
-SHAWN-

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joe.marsiglia Apr 5, 2006 6:38 PM
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Hey guys,

Has anybody written a program to encode/decode Manchester data? I need to program and read back a device that has a 64 bit stream.
Clock = 15.625 Hz so bit time is 64ms. Total meaasge = 4.096 s.

Start           4 bits
Message      52 bits
Checksum      4 bits
Gap          4 bits

Any help is appreciated. Thanks

Joe Marsiglia
Unison Industries

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VRFuser Apr 5, 2006 9:27 PM
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Search the "unofficial vrf archive" at "www.oswegosw.com/vrf_archive/".
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VRFuser Apr 5, 2006 9:53 PM
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Shawn,
Thank you very much. Your example was great. So now that I have code that does what I need I'd like to understand it. Thus a few questions.
I looked up RegOpenKey in Dan Appleman's win32 api book. I assume Registry.LocalMachine.OpenSubKey is the equivalent to RegOpenKey. Right?
This returns a handle to the key? Or a regkey object? Or is this the samr thing?
The next line where you use the dot operator on key would imply its an object but the regOpenKey doesn't return an object.
kevin

-----Original Message-----
From: Shawn Fessenden [mailto:shawnfess@comcast.net]
Sent: Wednesday, April 05, 2006 10:28 AM
To: VRF
Subject: RE: [vrf] reading the computer description from the registry using .NET in VEE

> I'm entering a text/string its looking for a regkey object?

Ah, a problem sent as if by request.

Folks, here's a perfect example of how OO can mess you up. The necessary information is hidden in the class. And it doesn't matter if you're using .NET or ActiveX in this case - both are equally obscure.

Yup, it's looking for a RegistryKey. All the registry functions take a handle to an open key as the first parameter. This is not apparent unless you're use to using the real functions from advapi32. The first parameter is HKLMSYSTEMCurrentControlSetServiceslanmanserverparameters". Note that it's not "ControlSet001" - always use CurrentControlSet.

This is actually a two step process. First you have to open "SYSTEMCurrentControlSetServiceslanmanserverparameters". The previously opened key in this case is HKLM. Of course, you don't know that unless you read the documentation for RegOpenKey, in which you find that HKEY_LOCAL_MACHINE is a constant.

>From winreg.h you find that HKLM is 0x80000002. Unfortunately you have
>to
turn that into a RegistryKey. Fortunately the assembly has the static LocalMachine value that's already an open key. This all works backwards more or less, so it goes like this:

key =
Registry.LocalMachine.OpenSubKey("SYSTEM\CurrentControlSet\Services\lanma
nserver\parameters");
comment = key.GetValue("srvcomment", asClrType("No comment", System.Object));

Why bother using the C API? Because *that's* where all the functionality comes from. Once you understand that you understand nearly any other way of looking at the API including ActiveX, .NET and anything else that is likely to rear it's ugly head.
-SHAWN-

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willie.kiely Apr 6, 2006 10:31 AM
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"><HTML><HEAD><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"><META NAME="Generator" CONTENT="MS Exchange Server version 6.5.7226.0"><TITLE>RE: [vrf] Manchester Code</TITLE></HEAD><BODY><DIV id=idOWAReplyText2423 dir=ltr><DIV dir=ltr><FONT face=Arial color=#000000 size=2>Isn't manchester encoding a fundamental way of transporting bits under a clock system.....spike up for a series of 1's, ans spike down for the next series of 0's.......compression possibly 50%</FONT></DIV><DIV dir=ltr><FONT face=Arial color=#000000 size=2></FONT> </DIV><DIV dir=ltr><FONT face=Arial color=#000000 size=2>.....or is that why I got a D in digital systems?</FONT></DIV></DIV><DIV dir=ltr> </DIV><DIV dir=ltr>Regards,<BR><HR tabIndex=-1><FONT face=Tahoma size=2><B>From:</B> Shawn Fessenden [mailto:shawnfess@comcast.net]<BR><B>Sent:</B> Thu 06/04/2006 18:27<BR><B>To:</B> VRF<BR><B>Subject:</B> RE: [vrf] Manchester Code<BR></FONT><BR></DIV><DIV><P><FONT size=2>> Has anybody written a program to</FONT> <BR><FONT size=2>> encode/decode Manchester data?</FONT> </P><P><FONT size=2>What's the physical layer?</FONT> <BR><FONT size=2>(no I haven't done it, I'm just curious)</FONT> <BR><FONT size=2>-SHAWN- </FONT></P></DIV><BR>---<BR>You are currently subscribed to vrf as: rsb@soco.agilent.com<BR>To subscribe please send an email to: "vrf-request@lists.it.agilent.com" with the word subscribe in the message body.<BR>To unsubscribe send a blank email to "leave-vrf@it.lists.it.agilent.com".<BR>To send messages to this mailing list, email "vrf@agilent.com". <BR>If you need help with the mailing list send a message to<BR>"owner-vrf@it.lists.it.agilent.com".<BR>Search the "unofficial vrf archive" at "www.oswegosw.com/vrf_archive/".</BODY></HTML>
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VRFuser Apr 6, 2006 10:48 AM
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Isn't manchester encoding a fundamental way of transporting bits under a clock system.....spike up for a series of 1's, ans spike down for the next series of 0's.......compression possibly 50%
Â
.....or is that why I got a D in digital systems?
Â
Regards,

Â _____ Â

From: Shawn Fessenden [mailto:shawnfess@comcast.net]
Sent: Thu 06/04/2006 18:27
To: VRF
Subject: RE: [vrf] Manchester Code

> Has anybody written a program to
> encode/decode Manchester data?

What's the physical layer?
(no I haven't done it, I'm just curious)
-SHAWN-

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VRFuser Apr 6, 2006 11:27 AM
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> Has anybody written a program to
> encode/decode Manchester data?

What's the physical layer?
(no I haven't done it, I'm just curious)
-SHAWN-
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