Hello, I'm in a project and I'm using the SD_card. How I can get the fastest speed reading sd card? What kind of sd_card recomindan me, or else I can use that can read the data as fast as possible?
Reading the data is limited by the Read access specification for the SD card. You can't get around that. Storing data is limited by the Write time but if the data is analog data from an analog pin the speed can be increased by writing BIN files every 512 bytes instead of writing after each analog conversion.
The higher the Class, the faster the card. MP3 can use lower Class than a camera in video mode.
I find bigger capacity flash devices slower but maybe because I buy cheaper, slower Class cards.
Smallest I have are 2G.
Read and write in burst mode for speed, IIRC either 32 (or is it 34?) bytes or more at a time.
If you can, have only 1 card on the SPI bus to keep it selected and not have to initialize and set seek over and over.
AVR serial ports are all capable of full speed master-mode SPI. A 1284P has 2 serial and 1 SPI port. A MEGA2560 has 4 serial and 1 SPI. If you keep 1 file per card you can save time that way.