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laserted
Joined: 25 Apr 2008 Posts: 1
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Transflash SD vs MMC by SPI |
Posted: Fri Apr 25, 2008 10:42 am |
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I've been implementing 3.3 and 5v MMC and SD cards on PICs for some time now with success, but recently received a large batch of TransFlash SD cards that won't work for me - won't even get past init. They're micro-SD cards of SanDisk descent, in original SanDisk micro-to-standard SD adapters. I have sizes from 16mb to 128mb, and am trying with both Fat and Fat32 libraries. The cards operate fine in my Linux and Win32 machines, as well as other embedded devices (cameras, PDAs, MP3 etc).
I fully realize that SPI (as implemented in these libraries, at least) is a compatibility mode of MMC, not necessarily SD or anything else for that matter - does anyone have recent experience working with Transflash/MicroSD successfully?
I'm not too concerned if I can't use these cards; 1GB cards in full-size SD are so cheap these days to be a non-issue; just when you only need to play back 2mb worth of data, sending out 1GB cards seems silly....
Thanks,
Ted. |
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ckielstra
Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands
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Posted: Fri Apr 25, 2008 12:11 pm |
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The SPI-bus is an optional communication mode in the microSD standard (compulsory for normal SD). I don't know how you can check if SPI is supported or not.
1-bit bus mode is compulsory but that is a major rewrite of your code. |
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asmallri
Joined: 12 Aug 2004 Posts: 1635 Location: Perth, Australia
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Re: Transflash SD vs MMC by SPI |
Posted: Fri Apr 25, 2008 12:29 pm |
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laserted wrote: | I've been implementing 3.3 and 5v MMC and SD cards on PICs for some time now with success, but recently received a large batch of TransFlash SD cards that won't work for me - won't even get past init. They're micro-SD cards of SanDisk descent, in original SanDisk micro-to-standard SD adapters. I have sizes from 16mb to 128mb, and am trying with both Fat and Fat32 libraries. The cards operate fine in my Linux and Win32 machines, as well as other embedded devices (cameras, PDAs, MP3 etc).
I fully realize that SPI (as implemented in these libraries, at least) is a compatibility mode of MMC, not necessarily SD or anything else for that matter - does anyone have recent experience working with Transflash/MicroSD successfully?
I'm not too concerned if I can't use these cards; 1GB cards in full-size SD are so cheap these days to be a non-issue; just when you only need to play back 2mb worth of data, sending out 1GB cards seems silly....
Thanks,
Ted. |
I am successfully using 2G MicroSD cards. You might want to try performing a SDHC initialization sequence on these cards. _________________ Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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