Product Idea: USB Flash Drives

[barray]

Unfortunately, that multiplication doesn't apply.   According to the feature list in the BL602 datasheet, the 40 Mbit/s limit applies to the general-purpose SPI interface that the SPI-to-USB bridge would be connected to.  Thus, whatever happens inside the storage device cannot leave it faster than about 4 MB/s, which is slow.  The datasheet actually provides no information about the maximum speed of the quad-SPI flash interface, but the general-purpose SPI already presents a bottleneck.

In theory it could still be connected to the QSPI bus if it's not attached to a DMA buffer or we dynamically allocate DMA buffers to QSPI devices? If re-mapping DMA is fast then this shouldn't be so bad. (This assumes that my four SPI device limit is based on the number of DMA buffers.)

Also if we are running memory mirroring, we could perhaps write to two devices at the same time. The data lines should look identical anyway (it might get complicated if we get bad blocks, but we can cross that bridge later). This would reduce the number of "unique" QSPI devices and increase throughput.

I agree on the risk, with all that requiring a lot of work, and with many things still unknown.  The BL602 "baseboard" might be very well used as a stepping stone, with a clear intention to upgrade to a better "baseboard" down the road.  However, my primary concern is that a lot of work would be poured into creating a storage device that would hardly be much more than a proof of concept, so it might be good to plot a clear path for the "baseboard" upgrade from the beginning.

Well we would eventually want to move towards a single PCB anyway, so perhaps once everything else is working then we can move to a faster board. I still believe there are options to squeeze more speed out of the device though as mentioned above.

I believe a new baseboard would be something much more within Pine64's remit as they will have some internal vision with roadmaps that consider the larger picture, including production.

I also think it's worth seeing what comes of this RISC-V SBC (PineOne?) in a few months as we learn more, it might be too overpowered or just right.

Please, don't get me wrong.  Crafting an open storage device that's built using open-source tools and provides about 4 MB/s through its USB interface is no small feat and I'd be happy to see it ticking.  However, I'm pretty sure that not many other people would share the excitement about those 4 MB/s.

Maybe, but I think such a hat could make the BL602 into some cool projects even at such a low speed, like an MP3 player or micro-server for static files, for example. Or the memory could be used for storing video for some CCTV like IoT device in a circular buffer. I'm sure having a lot of memory attached to such a device could already be interesting, even if the transfer is slow via USB.