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DS2411 1-Wire

 
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DS2411 1-Wire
PostPosted: Wed Mar 23, 2005 7:41 am     Reply with quote
Hi !

I'd like to use the DS2411 1-Wire for a project.
Could anybody provide me some C code?

Many thanks.
jds-pic



Joined: 17 Sep 2003
Posts: 205

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Re: DS2411 1-Wire
PostPosted: Fri Mar 25, 2005 10:42 am     Reply with quote
Anonymous wrote:
Hi !
I'd like to use the DS2411 1-Wire for a project.
Could anybody provide me some C code?
Many thanks.

start here, with some onewire functions from the code library forum:
http://www.ccsinfo.com/forum/viewtopic.php?t=19520

then download and read the ds2411 datasheet:
http://pdfserv.maxim-ic.com/en/ds/DS2411.pdf

and 15 minutes later you have a working program.

jds-pic
Guest
PostPosted: Tue Mar 29, 2005 9:28 am     Reply with quote
I found how it works more or less but i just wondered why the CRC does not match with the last 8 bit.

Anyway, i find a serial number with hexadecimal numbers which seems to be correct.

Thanks.
Guest
PostPosted: Tue Mar 29, 2005 9:30 am     Reply with quote
ok thanks not that easy :(
jds-pic



Joined: 17 Sep 2003
Posts: 205

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PostPosted: Tue Mar 29, 2005 9:51 am     Reply with quote
Anonymous wrote:
Anyway, i find a serial number with hexadecimal numbers which seems to be correct.

when i was starting out with 1wire, i had the same concern -- "how do i know my crc routine is working?"
it was very frustrating since my code for the 1wire device on the prototype board i was using kept returning "0x00" as the crc byte.
i debugged and recompiled my code about 87 times, looking for the error i had obviously made.
finally, i sat down and *BY HAND* calculated the crc for the device bytes.








turns out the crc *was* 0x00. i had a 1/255 chance of getting a part like this, and i did!

jds-pic

ps
if you have the rom space, you can use the lookup table method rather than the computation method. it's the std time-vs-space tradeoff. but quicly implementing the lookup table (even by hand as i did) will allow you to verify that the computational method is indeed correct.
see
http://pdfserv.maxim-ic.com/arpdf/AppNotes/app27.pdf
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