How to calculate CRC16 checksum for iButton

[ashwini kotwal]

I have made small iButton project. I want to calculate CRC-16 checksum in which polynomial is x^16 + x^15 + x^2 + 1. If I use 'writePagePacket' function for writing data on iButton then it gets automatically calculated, how will I get CRC checksum using 'write' function only?

[Andre_Pretorius]

Hi there
I am mot famiriar with the ibutton you work on but here are my code i use in a modbus protocol to calculate CRC16 cheksums

Calcul_CRC16:

CRC16=$FFFF
For i=0 to (DataAmount -3)
CRC16=CRC16^DATACRC[i]
For j=1 to 8
IF CRC16.Bit0=1 Then
CRC16=$A001^(CRC16>>1)
Else
CRC16=CRC16>>1
EndIF
Next j
Next i
Return

hope it helps

[Ioannis]

And if you change the

For j=1 to 8

to

For j=0 to 7

you will gain and a few memory bytes!

Ioannis

[Andre_Pretorius]

i am not sure only one way to find out try and try again

[Darrel Taylor]

Dallas CRC16 Routines (Tom Estes)
https://www.picbasic.co.uk/forum/showthread.php?t=1745

I haven't used the CRC16 routines, but Tom's CRC8 worked great on a project of mine.
<br>

[ashwini kotwal]

Thanks for replying me.
I tried the given code, but I am not able to write it in C#.Net. As I don't know the varaible type of CRC16. Can you please explain me?