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SD Card Speed Clock

 
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mansur

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Joined: 21 Feb 2013
Posts: 8
Location: Jakarta

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PostPosted: Wed May 16, 2018 2:27 am    Post subject: SD Card Speed Clock Reply with quote

Dear All,
How many the maximum speed if we use atxmega to write the uSD Card (class 6) with logic converter (3v3 level). we want to use the pll clock until 48 MHZ or 64MHZ.
Yesterday i try to write the uSD card with logic converter with crystal set=32 MHZ and SPI clock CLK2 the result is success, but i try to edit and change the main clock to 48 MHZ, the uSD card not respons if CLK2, i'ts mean the logic converter not match with this clock.
any body already try without logic converter and pll clock?

(BASCOM-AVR version : 2.0.8.1 , Latest : 2.0.8.1 )

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Mansur. H
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Evert :-)

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Joined: 18 Feb 2005
Posts: 2061

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PostPosted: Wed May 16, 2018 1:02 pm    Post subject: Reply with quote

Max default clock speed for a sd card is 48Mhz.
If you power up an sd-card it will always work on 3.3V, 1 bit bus and max. 45mhz clock. This to make all the new fast cards downwards compatible.
If you want a higher clock speed, lower voltage (1.8V) or change bus width you have to negotiate with the card to change the settings. Ask the card what he (or she) is capable of and then change the settings.

I did it in C, but never in Bascom. Hope you can find some examples else it's a long way to go.

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mansur

Bascom Member



Joined: 21 Feb 2013
Posts: 8
Location: Jakarta

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PostPosted: Tue May 22, 2018 5:24 am    Post subject: Reply with quote

[quote=\"Evert Smile\"]Max default clock speed for a sd card is 48Mhz.
If you power up an sd-card it will always work on 3.3V, 1 bit bus and max. 45mhz clock. This to make all the new fast cards downwards compatible.
If you want a higher clock speed, lower voltage (1.8V) or change bus width you have to negotiate with the card to change the settings. Ask the card what he (or she) is capable of and then change the settings.

I did it in C, but never in Bascom. Hope you can find some examples else it\'s a long way to go.[/quote]

Hi evert,
thanks for your advice, i will try to replace the logic converter for sd card.

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Mansur. H
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EDC

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Joined: 26 Mar 2014
Posts: 509

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PostPosted: Tue May 22, 2018 1:56 pm    Post subject: Reply with quote

With Xmega you dont need the level converter. Xmega 3.3V ... SDCard 3.3V
To the Xmega I always link SDCard directly.
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