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Topic: Why do some microSD cards work others don't? (Read 235 times) previous topic - next topic

morr8362

Why do some microSD cards work others don't?

I have several larger microSDHC cards (8gb-16gb) which can be read and written to with my 3.3v pro mini. I bought some 128mb cards that fail to initialize using Card info sketches from the sd and sdFat libraries.

I have reformatted the cards using:
https://www.sdcard.org/downloads/formatter_4/index.html



The only answer I have been able to find is "some cards just don't work"

Are there any recommendations for getting the right cards?

 

morr8362

For others wandering down this path I found some help on reddit:

https://www.reddit.com/r/arduino/comments/b3vpz3/why_do_some_microsd_cards_work_while_others_dont/

pert

Do you have a feeling that one specific answer there was more likely to be the correct one?

I have heard that different cards draw different amounts of current. My hypothesis was that the non-working cards were drawing more current than your power supply could manage. However, that's purely a guess. I see that someone on Reddit mentioned the same idea.

ieee488

SD cards are meant to work with 5V systems as far as I know.

Asking them to work at 3.3V is stretching.

pert

I think it's the opposite. SD cards are 3.3 V. However, many (though not all) common Arduino SD modules contain level shifting hardware so that they can be used with a 5 V Arduino. If you try to use one of those with a 3.3 V Arduino, that could be problematic.

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