nRF52840 USBD MSC transfer speed

RE: nRF52840 USBD MSC transfer speed

nrffans — Thu, 24 Jul 2025 01:10:52 GMT

Could you provide an example of this non-zephyr project

thanks

RE: nRF52840 USBD MSC transfer speed

doowl — Wed, 29 Mar 2023 15:04:46 GMT

Gotcha, thanks for the confirmation! I'm actually using the USB MSC implementation from the nRF5 SDK, but it is probably similar (if not the same). I was primarily interested in write speed.

[quote userid="18935" url="~/f/nordic-q-a/98205/nrf52840-usbd-msc-transfer-speed/417852"]I belive that USB and the card is not read/written to at the same time but one after the other.[/quote]

If I understand correctly, you mean that it is buffered on the nRF first before writing it to the SD card?

RE: nRF52840 USBD MSC transfer speed

Turbo J — Tue, 28 Mar 2023 10:57:00 GMT

I've been working with SD cards for a while, the 350KByte/sec is the expected speed when working with one sector at a time. This is expected behavior, especially since I belive that USB and the card is not read/written to at the same time but one after the other.

You can get up to interface speeds (either SPI or USB) with reading the SD card (next sectors) while writing the current one(s) to USB - but that would IMHO require serious changes to the USB MSC implementation in zephyr. I've done that in a non-zephyr project.