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Forum Index : Microcontroller and PC projects : SD cards and how to format them
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BobDevries Senior Member  Joined: 08/06/2011 Location: AustraliaPosts: 266 |
Hi all, I'm having some difficulty with using (previously used) SD cards. I *think* I know how to format them... there's a program called SD Formatter, or I can use the formatter built into "ëxplorer". which format should I use? NTFS, FAT, FAT32? I have one SD card which has survived since I started using it back when I got the Mono Maximite. Is there anything special I need to do to it? The card that's in use is a 4GB Verbatim. Regards, Bob Devries Bob Devries Dalby, QLD, Australia |
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MustardMan Senior Member Joined: 30/08/2019 Location: AustraliaPosts: 175 |
Hi Bob, AFIK NTFS formatted devices can't be used with MMbasic as it does not understand the file system. You can format FAT as long as the size limitations don't get you (or you are OK with wasting some space) as they are universally recognised by not just MMbasic, but just about any embedded system or operating system. FAT32 is (from my understanding) also usable with MMbasic. There might be a problem using it with older embedded systems (eg: older MP3 players, navigation devices, etc). |
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KeepIS Guru  Joined: 13/10/2014 Location: AustraliaPosts: 1345 |
ExFAT on cards > 32GB else FAT32. Mike. It's all too hard. Mike. |
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hitsware2 Guru Joined: 03/08/2019 Location: United StatesPosts: 705 |
Right .... FAT32 is pretty universally usable . ONE THING THOUGH ! SD cards do eventually ' wear out ' ( or something ? ) I have had more than one loose ability to be formatted ..... my site |
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SimpleSafeName Senior Member Joined: 28/07/2019 Location: United StatesPosts: 286 |
Having recently gone through this, here's what it took for me: Assuming a CMM2 board... Cards less than 8Gb are not recommended. Like KeepIS says, ExFAT on cards > 32GB else FAT32. Upgrade your firmware. And finally, if all else fails set this switch: OPTION SD TIMING CONSERVATIVE |
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| KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 1345 |
Latest Firmware comes default at Normal (was called CONSERVATIVE), new option of OPTION SD TIMING FAST. Mike It's all too hard. Mike. |
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| MustardMan Senior Member Joined: 30/08/2019 Location: AustraliaPosts: 175 |
The recommendation from Microsoft is to format >32GB cards with ExFAT, but I understood that ExFAT is a proprietary file system and to use/implement it requires payment to Microsoft. Hence, it is not very well supported outside of Windows operating systems. A bit like NTFS used to be until it was reverse engineered (and even so, many OSs still require booting a native Windows OS to fix NTFS problems). It is certainly possible to format cards of >32GB as FAT32, and I have done just that. Unfortunately that can lead to problems with *some* embedded devices as they assume anything over 32GB *will* be ExFAT without actually checking! Gparted does a fine job of formatting cards >32GB as FAT32. SimpleSafeName - why do you recommend against anything smaller than 8G? I regularly use 2G and 4G cards. The only reason I can think of is that they are now becoming difficult to buy! Cheers, |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8567 |
Cards over 32Mb formatted FAT32 are not supported on the CMM2 as they require a non-standard block size Experience has shown that some 4GB and many 2GB cards do not meet the basic performance standards defined for SPI operation and don't work reliably |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2285 |
i don't know about in the rest of the world, but here in New Zealand a 16gb SD card can be brought new for as little as nz$5, smaller cards are on stock clearance. similarly, 8gb USB flash drives are being phased out by the major suppliers, replaced by 16gb at the bottom end of the price range (approx nz$8). one company i work with (who use several hundred flash drives per year) have been forced to go from using 8gb to using 16gb for jobs. i can see 32gb becoming the new 'bottom end' by the end of the year, thereafter 64gb/exFAT will start to become the next 'bottom end'. like it or not, if FAT32 is limited to 32gb there will be a supply issue for new, usable SD cards in the future. cheers, rob :-) |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 8567 |
FAT32 is limited to 32GB, exFAT is not and is supported. exFAT design docs are now openly available from Microsoft. Microsoft open source blog August 28, 2019 |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2285 |
"exFAT is not and is supported": from this i assume the CMM2 supports cards formatted as exFAT? if so, then there is no problem  cheers, rob :-) |
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| MustardMan Senior Member Joined: 30/08/2019 Location: AustraliaPosts: 175 |
Good to know ExFAT is supported, and that Microsoft has opened it up. @robert.rozee : I suspected that purchasing was going to be the issue! Still, I suppose if you don't like ExFAT, and since the cards are so dang cheap, there would not be a problem formatting cards >32GB *as* 32GB and wasting the rest. Or would it? |
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