uart, dabort_handler

Ok Paul,

Thanks a lot !

Best regards,
Kris

-----Original Message-----
From: A... [mailto:A...] On Behalf Of Paul Curtis
Sent: Tuesday, 24 June 2008 2:25 AM
To: A...
Subject: RE: [AT91SAM] SDIO WLAN 802.11 7 bit CRC calc

Kris,

> Has anyone ever worked out what the exact algorithm is for SDIO (1.1 or
> 2.0) to compute the 7 bit
> CRC in commands ?
> I'm testing with a Spectec SDW-820 802.11b card, and can talk SPI to it
> fine it seems, I can read
> the OCR and am about to try reading CIS pointer etc.
> However, I'd like to try use SD 1 bit.
>
> As far as I can tell, the polynomial is G(x)= x7+x3+1 but I'm not sure
> how the CRC itself is
> performed( ie. do you init the CRC with 0 or all ones etc.) Other than
> that I know that the CRC +
> stop bit + 32 bits of 0 on CMD0 = 0x95,

No. For CRC-7 you do not pour 32 zero bits through for final computation.

> does anyone know how the code should calc the CRC ?

Of course!

> Is it perhaps the same as a standard CCITT 16 bit calc, except that 7
> bits are accumulated?

No, it's not.

> I'm actually wondering about the returned 16 bit CRC as well.

I'll send you the CRC code I wrote.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks for ARM, MSP430, AVR, MAXQ, and now Cortex-M3 processors

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Kris
I've found this page to be very helpful over the years.
http://www.zorc.breitbandkatze.de/crc.html

-Bill Knight
R O SoftWare
microbit wrote:
> Hi All,
>
> Has anyone ever worked out what the exact algorithm is for SDIO (1.1 or 2.0) to compute the 7 bit
> CRC in commands ?
> I'm testing with a Spectec SDW-820 802.11b card, and can talk SPI to it fine it seems, I can read
> the OCR and am about to try reading CIS pointer etc.
> However, I'd like to try use SD 1 bit.
>
> As far as I can tell, the polynomial is G(x)= x7+x3+1 but I'm not sure how the CRC itself is
> performed( ie. do you init the CRC with 0 or all ones etc.) Other than that I know that the CRC +
> stop bit + 32 bits of 0 on CMD0 = 0x95, does anyone know how the code should calc the CRC ?
> Is it perhaps the same as a standard CCITT 16 bit calc, except that 7 bits are accumulated?
> I'm actually wondering about the returned 16 bit CRC as well.
>
> B rgds
> Kris

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Thanks Bill !

B rgds
Kris

-----Original Message-----
From: A... [mailto:A...] On Behalf Of Bill Knight
Sent: Tuesday, 24 June 2008 5:25 AM
To: A...
Subject: Re: [AT91SAM] SDIO WLAN 802.11 7 bit CRC calc

Kris
I've found this page to be very helpful over the years.
http://www.zorc.breitbandkatze.de/crc.html

-Bill Knight
R O SoftWare
Start a New Thread