Varying eMMC sizes on the 4GB Beaglebone Green Wireless

We are noticing different eMMC sizes on our 4GB Beaglebone Green Wireless. So far we identified devices with these 2 sizes:

  • 7,634,944 sectors x 512 bytes per sector = 3,909,091,328 bytes = 3,728 MiB (Mebibyte)
  • 7,405,568 sectors x 512 bytes per sector = 3,791,650,816 bytes = 3,616 MiB (Mebibyte)

Are there other known sizes? We need every byte of space but we also want to design our eMMC images to fit them all.

Thank you.

Follow up with more into about this, my colleague dug around some more:

Out of curiosity I went through the documentation of the BB. My initial guess was, that there might be two revision of the board out there with different eMMC chips. This is not the case. There is only one version of the BB Green Wireless and the eMMC in charge is a “MTFC4GACAAAM-1M WT”. The corresponding datasheet mentions a smart mechanism, that disables faulty NAND blocks and replaces them with spare blocks (as long as they are available). My guess now: the boards with lower eMMC capacity are simply older or have experienced non optimal conditions (e.g. higher temperatures) during their lifespan.

Could that be the reason here?

That is Micron, Seeed uses Kingston nowdays…

The issue, Micron and Kingston do not agree on what “4GB” is. This is industry wide issue…

Kingston over the years has been more consistent, whereas Micron would tweak the flash sizes between different 2GB and 4GB modules (with at-least different part numbers…)

Other nand/emmc suppliers do the exact same thing…