Help with hard core HEX programing question

[piercedan]

For anyone good at HEX CRC algorithms or iButtons. If you fit this catagory and want to help with what is probably a simple problem, let me know.

[Turbo V6 Camaro]

post to problem i know a little bit, i may at least be able to point you in the right diretion

[piercedan]

Cool, I will in the morning.

Thanks!

[mike h]

the only hex's I know about are Callaway Hex's. I golf too much.

[12secondv6]

Hex bits... I know about those??? [img]tongue.gif[/img]

[chas]

i take it you need to generate a crc for a sequence of bytes and have been give the (binary) polynomial or crc in hex?

[piercedan]

i take it you need to generate a crc for a sequence of bytes and have been give the (binary) polynomial or crc in hex?

That is pretty close. I will post the problem in the morning, but I think you have a good head start.

[piercedan]

Here is the important part for starting this:
(link to full text: http://pdfserv.maxim-ic.com/en/ds/DS...DS1990A-F5.pdf )

64-BIT LASERED ROM
Each DS1990A contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code. The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. See Figure 2 for details. The 1-
Wire CRC is generated using a polynomial generator consisting of a Shift and XOR gates as shown in Figure 3.

The polynomial is X8 + X5 + X4 + 1. Additional information about the Dallas 1-Wire Cyclic Redundancy Check is available in Application Note 27.

The Shift register bits are initialized to 0. Then starting with the least significant bit of the family code, one bit at a time is shifted in. After the 8th bit of the family code has been entered, then the serial number is entered. After the 48th bit of the serial number has been entered, the Shift register contains the CRC value. Shifting in the 8 bits of CRC returns the Shift register to all 0s.

____________________________________

I need to know how to use the ID to generate the code in parenthesis below each ID line.


ID: 820000005f16c101 (01 c1 16 5f 00 00 00 82)

(96671713)

ID: 820000035f190d01 (01 0d 19 5f 03 00 00 82)

(8bbf4dd6)

Thanks for the help!

[ April 05, 2005, 03:29 PM: Message edited by: piercedan ]