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sd card comparison

December 26, 2016

This post discusses sd card comparison.

what is the difference between sd card and sdhc card, and sdxc card
They are physically the same. They differ in storage capacity, file system, and data transmission rate.

  • The capacity of sd card is at most 2GB. The file system is 16FAT.
  • The capacity of sdhc card is more than 2GB but at most 32GB. The file system is FAT32
  • The capacity of sdhx card is more than 32GB but at most 2TB. The file system is exFAT.

class and speed

  • class 2: data transmission rate is at least 2MB/s
  • class 4: data transmission rate is at least 4MB/s
  • class 6: data transmission rate is at least 6MB/s
  • class 8: data transmission rate is at least 8MB/s
  • class 10: data transmission rate is at least 10MB/s

test of data transmission rate
I tested a 16GB class 10 SDHC card. It takes 74 seconds to write 1 GB data to sdcard. The test data transmission rate is about 13MB/s.

dd if=/dev/zero of=/${SD_CARD_PATH}/a.dat bs=1024 count=$((1024*1024))

conclusion
This post discusses sd card comparison. And test data transmission rate of a sdhc card.

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