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Forum Index : Microcontroller and PC projects : How many files can MM use on SD card?
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9307 |
Just an update for you all: - IT WAS THE SD CARD. I tried lots of different ones, but the low-capacity ones are just too slow to work right with the file searching method I am planning to use - I MIGHT rethink that, but probably not - SD cards are very fast nowadays, so... The 16MB, 128MB, 256MB, 512MB and 1GB cards I tried all gave varying results, with the 16MB card being the slowest taking 15.8 seconds to find the file, and getting slightly faster with each larger card till about 3.8 seconds on the 1GB card. However, once I put in a 4GB class-6 SD card, the search time dropped to 441ms for the exact same search, so a class-6 or faster card is the solution. Curses - I was hoping to use some of the older cards. 16MB is not much use for anything else these days, but I figured it would be perfect for the MM or CMM!  Smoke makes things work. When the smoke gets out, it stops! |
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djuqa Guru  Joined: 23/11/2011 Location: AustraliaPosts: 447 |
Why use small capacity cards Topbuy today only has Large Fast ones real cheap from 2.98 (2gb MicroSd) including shipping, the SanDisk microSDHC 8GB,class 4,With SD Adapter only 5.98 All the way to a Class 10 64gb for 70$ Offer Page VK4MU MicroController Units |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9307 |
Oh absolutely. I totally agree with you. I was just hoping to find a home for one or two of my older ones, cos I can't bring myself to biff them. ...but I think that will be the outcome sooner rather then later. Smoke makes things work. When the smoke gets out, it stops! |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9307 |
Also tried a 16GB Class-10 SD card, but it's speed was about the same as the class-6. PROBABLY because the MM or CMM can clock the SD card up to around the class-4 or class-6 range, but I doubt the MM has the speed to clock the card at 10MB per second. :D I don't have any class-4 cards, or anything less then class-6 that is marked on the card, anyway. Smoke makes things work. When the smoke gets out, it stops! |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3194 |
In all variants of MMBasic the SD card is clocked at 20MHz. This is just the clock speed, not the transfer speed (which is controlled by the card). Geoff Graham - http://geoffg.net |
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