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karsia
Joined: 26 Feb 2010
Posts: 5
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| SD card problem |
 Posted: Mon Mar 29, 2010 8:39 am |
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| I am trying to use sd card. It is not error when I am sending data but when I am trying to read it is reading something different or nothing. So what can be the problem ? (compiler version is 4.068, and microcontroller is pic18f4520) please help....... need this hardly. |
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karsia
Joined: 26 Feb 2010
Posts: 5
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| Posted: Mon Mar 29, 2010 8:56 am |
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| and i have built the real circuit too. and set all voltage levels as 3.3 v (with resistors),from pic to card and 5v from card to pic(with 74hct125). |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Mon Mar 29, 2010 11:15 pm |
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| karsia wrote: | | and i have built the real circuit too. and set all voltage levels as 3.3 v (with resistors),from pic to card and 5v from card to pic(with 74hct125). |
A common problem is forgetting the pull-up resistor on the DO line of the card. In this event the card may or may not successfully initialize. You can find some reference designs for SD/MMC hardware integration on my site.
Another common problem is insufficient power supply filtering on the 3.3 volt rail. The card can draw up to 100mA for a very small amount of time during a write operation. Insufficient power supply filtering (decoupling and filtering) can result in a DIP on the power rail to the SD card causing it to reset or misbehave.
Regards, Andrew
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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karsia
Joined: 26 Feb 2010
Posts: 5
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| Posted: Thu Apr 01, 2010 11:52 am |
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thank you so much . the problem is about pull up resistor. now it is working. thank you so much again
King Regarts Aslan |
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