Subject:
|
Re: LNP Repost (Me banging on about checksums)
|
Newsgroups:
|
lugnet.robotics.rcx.legos
|
Date:
|
Thu, 29 Jul 1999 19:30:06 GMT
|
Viewed:
|
925 times
|
| |
|
|
In lugnet.robotics.rcx.legos, Kekoa Proudfoot writes:
> Regarding the CRC, I would use a CRC8 unless practice shows that a CRC16 is
> required. I would look ahead to the day when a CRC16 is used and choose
> the more important byte of the CRC16 to be the CRC8. Tagging an extra byte
> onto the end of a message can then be completely backwards compatible
> assuming you write the software correctly.
>
> -Kekoa
With much respect, I would suggest that CRC8 is probably not sufficient,
especially if we go for a broadcast (Ethernet) solution, where lots of
collisions, and hence errors, will probably occur - with CRC8 you will
probably miss about 1 in 256 errors, which sounds rather high.
Can I suggest the checksum mechanism I recently posted - we can have a 16 bit
checksum at lower CPU code size & execution speed costs, but with error
detection almost the equal of any CRC16.
This is a software protocol, lets use a software solution, not a hardware
solution!
Kevin.
P.S. Sorry - I promise not to mention it again!!!!
|
|
Message has 1 Reply:
 | | Re: LNP Repost (Me banging on about checksums)
|
| (...) You will miss about 1 in 256 errors that you do not catch earlier using collision detection. I think your error rate per message will be much less than 1 in 256 if you (can?) get the collision detection code right. But we shouldn't argue the (...) (25 years ago, 29-Jul-99, to lugnet.robotics.rcx.legos)
|
Message is in Reply To:
| | Re: LNP Repost
|
| (...) My only thoughts are that not everybody will need or want the generality of port support in the protocol. I would suggest reordering the first four bytes, moving the payload length up toward the front, and defining it to explicitly include the (...) (25 years ago, 28-Jul-99, to lugnet.robotics.rcx.legos)
|
21 Messages in This Thread:
 
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
