Product Idea: USB Flash Drives

[barray]

Sorry for lack of reply, for some reason I didn't get a notification...

You've laid it out very well, but the second point is the blocker.  We have to select the main chip first, but I'm really not sure which way to go.  Our direction so far has been to use the BL602, which seems rather fine, but it's still a can of worms that would surely come with more than a few issues, unknowns and unforeseen constraints.  We should also keep in mind that a BL602-based storage device would be rather slow, and at this point in time I'm pretty sure that we'll, unfortunately, end up getting no support from Pine64.

Sure, but we can get support from the community. Also any improvements/fixes also benefit the community. I imagine we will need a more powerful controller, but I think the BL602 is a great place to start. Even getting something working at a slow speed will be a massive achievement.

Perhaps we look at this differently - we're not aiming to build the final product, merely a proof of concept? If it even half works and we start to get some interest, I think we could attract more support.

Also, please have a look at the STM32 H7 microcontrollers.  The specs look very good, there's support for SDR/DDR quad-SPI interface (up to 256 MB), two 1-/4-/8-bit SD/MMC SDR104/HS200 interfaces (hmm, RAID1 across two microSD cards or, even better, two eMMC modules?), high-speed (480 Mbit/s) USB 2.0 device interface, and even an Ethernet MAC (100 Mbit/s only, though), but where would we start from the software side?  Though, a complete and very detailed reference manual is available and the GNU toolchain for Cortex-M7 is readily available.

Hacking about on a Cortex-M7 will be non-trivial... I've done this sort of work before and it took a lot of engineers several months getting even a basic framework up and running reliably.

Not a problem.   According to the Rock64 v3 schematic, it is possible to control (i.e. cut) the power supply to its USB ports, using one of the GPIO pins of the SoC.  I'd also suggest that we use Rock64, because it's a more powerful SBC than Pine A64-LTS, and has a USB 3.0 port as well.

Yeah, that would be the way to go.

Quite frankly, somehow I missed that link, but now I had a look at the W25N datasheet.  As far as I can see, the W25N has on-chip ECC and management of bad blocks, but doesn't do wear leveling on its own.  Based on that, all acknowledged write operations should actually reach the flash.  Thus, I'd say that it strikes a good balance.

We can always swap it out for something else at a later date - it's just cheap and simple. Once we have something basic up and running we could look to make it more complex.

It's very easily possible that the price difference becomes negligible in larger quantities.  My remark was based on a limited insight into the prices quoted by JLCPCB for different PCB colors.

I recently got some PCBs made with PCBway, colour didn't make a different in price at all (unless you wanted some special variant).

Related to this recent project, I also got automated schematic building and circuit verification working, export to Kicad and autorouting. I used this to build the recent project - will verify it all works when the PCB comes in a week's time or so.

Nice find.  They seem to charge about 40 EUR for a single 32 GB USB flash drive?  We might be able to match that price, but it would depend on the size of the initial batch.

I think that would be roughly where we're aiming for.