Hi,
We're using Arduino Mega and notice a problem with reading from microSD-card:
It works with one card, but not with another.
Card that works: 8GB, FAT32.
Card that doesnt work: 512MB, FAT. When formatted to FAT32 it still can't be read (data on card is only about 100kB, so card size shouldn't be the issue)
We'd like to know which card 'spec' is critical for proper communication/functioning.
Or might there be another reason why it's not working?
Io_oI:
We'd like to know which card 'spec' is critical for proper communication/functioning.
Compatibility with the SPI protocol.
For SD cards manufactured these days, SPI is more like legacy support; because it provides backwards compatibility with the old MMC standard.
The native protocol nowadays is SDIO, which I think only the Teensy boards and some STM32 are compatible with.
Nevertheless, I don't believe a 512-MB large SD card would be new enough to rule out SPI; so it's weird... Also, the library should handle all FAT variants except exFAT.
Have you tried the CardInfo example sketch?