SDHC/SDXC specs

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Locutus73
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SDHC/SDXC specs

Postby Locutus73 » Fri Feb 09, 2018 2:00 pm

Hi.
Which are the specs/limits regarding SD use in DE10-nano MiSTer?
Can be both SDHC and SDXC used?
Are there any size limits?
Which FAT families can be used?

Thank you in advance.
Best regards.

Locutus73

Sorgelig
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Re: SDHC/SDXC specs

Postby Sorgelig » Fri Feb 09, 2018 11:45 pm

both SDHC and SDXC can be used. I don't know what is the size limit. The biggest SD card i have is 128GB and it works. Probably any bigger size will work as long as it won't require new HW and spec will be the same. Even very new UHS-3 cards with additional pins still can be used in generic SD readers with reduced speed as far as i know.

FAT partition should be formatted into exFAT system as it doesn't have 4GB file size limit and more effective on big SD cards.
You need to use SD installer tool - it will automatically format the whole SD card.

alfishe
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Re: SDHC/SDXC specs

Postby alfishe » Sat Feb 10, 2018 2:56 am

Sorgelig wrote: Even very new UHS-3 cards with additional pins still can be used in generic SD readers with reduced speed as far as i know.


Yes, even UHS-3 cards will work but with hard limit on performance (since there are no extra pins line and 4 bit SD 3.0 interface working on 50MHz is used. Didn't make any formal performance measurements but if max burst transfer rate is 200Mbit/s then we cannot get more than ~20MBytes/s in reality.
I've never measured 104MHz clock frequency on SD so assuming that it always works on 50MHz.

See more: https://www.sdcard.org/developers/overv ... index.html


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