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RE: CRC16
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Hi Alan,
What RS485 protocol are you referring to?
I'm also doing some xAP stuff using AVR's. I'm creating a gateway that
converts between the Ethernet and the RS485 network.
It uses a AVR (Mega128) as the go between. From here it then talks to the
RS485 AVR slaves using my own protocol.
I found it easier to implememnt this way. Less xAP actually on the RS485
network.
Regards,
Neil Wrightson.
Australia.
From: xAP_developer@xxxxxxx [mailto:xAP_developer@xxxxxxx]
On Behalf Of hillbillies@xxxxxxx
Sent: Monday, 7 November 2011 11:20 AM
To: xAP_developer@xxxxxxx
Subject: [xAP_developer] CRC16
Hi Everybody,
New to the group, I only started looking xAP about a month ago.
I'm developing a RS485 style network with AVR devices. The wire protocol
should allow me to detect collisions but I would like to put CRC16 error
checking into the devices. Although the Protocol definition talks about
CRC16, it doesn't state which polynomial is the preferred one.
The AVR libraries have have already coded:
Optimized CRC-16 calculation.
Polynomial: x^16 + x^15 + x^2 + 1 (0xa001)
Initial value: 0xffff
Optimized CRC-CCITT calculation.
Polynomial: x^16 + x^12 + x^5 + 1 (0x8408)
Initial value: 0xffff
Optimized Dallas (now Maxim) iButton 8-bit CRC calculation.
Polynomial: x^8 + x^5 + x^4 + 1 (0x8C)
Initial value: 0x0
Optimized CRC-XMODEM calculation.
Polynomial: x^16 + x^12 + x^5 + 1 (0x1021)
Initial value: 0x0
Can anyone give me a pointer on which way to go?
Thanks
Alan
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<div class=WordSection1><p class=MsoNormal><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi
Alan,<o:p></o:p></span></p><p
class=MsoNormal><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p
class=MsoNormal><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>What
RS485 protocol are you referring
to?<o:p></o:p></span></p><p
class=MsoNormal><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><p
class=MsoNormal><span lang=EN-US
style='color:#1F497D'>I’m also doing some xAP stuff using
AVR’s. I’m creating a gateway that converts between the
Ethernet and
the RS485 network.<o:p></o:p></span></p><p
class=MsoNormal><span lang=EN-US style='color:#1F497D'>It uses a
AVR (Mega128) as the go between. From here it then talks to the RS485 AVR
slaves using my own
protocol.<o:p></o:p></span></p><p
class=MsoNormal><span lang=EN-US style='color:#1F497D'>I found it
easier to implememnt this way. Less xAP actually on the RS485 network.
<o:p></o:p></span></p><p
class=MsoNormal><span lang=EN-US
style='color:#1F497D'><o:p> </o:p></span></p><p
class=MsoNormal><span lang=EN-US style='color:#1F497D'>Regards,
<o:p></o:p></span></p><p
class=MsoNormal><b><span lang=EN-US
style='font-size:13.5pt;color:#1F497D'>Neil
Wrightson.<o:p></o:p></span></b></p><p
class=MsoNormal><b><span lang=EN-US
style='font-size:13.5pt;color:#1F497D'>Australia.</span></b><span
style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p></div><div><div
style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm
0cm'><p cla
ss=MsoNormal><b><span lang=EN-US
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
lang=EN-US
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
xAP_developer@xxxxxxx [mailto:xAP_de
veloper@xxxxxxx] <b>On Behalf Of
</b>hillbillies@xxxxxxx<br><b>Sent:</b> Monday, 7
November 2011 11:20 AM<br><b>To:</b>
xAP_developer@xxxxxxx<br><b>Subject:</b> [xAP_developer]
CRC16<o:p></o:p></span></p></div></div><p
class=MsoNormal><o:p> </o:p></p><p
class=MsoNormal> <o:p></o:p></p><div
id=ygrp-mlmsg><div id=ygrp-msg><div id=ygrp-text><p
style='margin-bottom:12.0pt'>Hi Everybody,<br><br>New to the
group, I only started looking xAP about a month ago.<br><br>I'm
developing a RS485 style network with AVR devices. The wire protocol should
allow me to detect collisions but I would like to put CRC16 error checking
into the devices. Although the Protocol definition talks about CRC16, it
doesn't state which polynomial is the preferred one.<br><br>The
AVR libraries have have already coded
:<br><br>Optimized CRC-16 calculation.<br>Polynomial:
x^16 + x^15 + x^2 + 1 (0xa001)<br>Initial value:
0xffff<br><br>Optimized CRC-CCITT
calculation.<br>Polynomial: x^
16 + x^12 + x^5 + 1 (0x8408)<br>Initial value:
0xffff<br><br>Optimized Dallas (now Maxim) iButton 8-bit CRC
calculation.<br>Polynomial: x^8 + x^5 + x^4 + 1
(0x8C)<br>Initial value: 0x0<br><br>Optimized CRC-XMODEM
calculation.<br>Polynomial: x^16 + x^12 + x^5 + 1
(0x1021)<br>Initial value: 0x0<br><br>Can anyone give me
a pointer on which way to
go?<br><br>Thanks<br><br>Alan<o:p></o:p></p></div><div><p
class=MsoNormal><span
style='color:white'><o:p></o:p></span></p></div></div>
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- References:
- CRC16
- From: hillbillies@xxxxxxxxx
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