Does anyone know if it is possible and/or have pointers or links on the question: If one has a device that expands its memory with a miniSD slot, is there any way to build an adapter that will let you connect something else to that slot and have it pretend to be miniSD storage? Example: I have a Sansa e280 mp3 player, 8gb with a miniSD slot. I'm looking for a way to hack together something that would let me connect either USB Mass storage devices or an IDE hard drive to the miniSD slot to expand the space. Thanks in advance for any tips!
Here is a website that has information on how a miniSD to SD adapter works -- it's a pass through. From there, someone might know what to do since SDs are great for storage in microcontroller data-logging applications.
SD cards have three modes: in one, you can just access it using SPI, which almost all modern microcontollers support. The other two you need a licence for, iirc. If your device is cheap and cheerful, you can bet it uses the SPI mode. Then you can hack a (fast) microcontroller to interface between it and a parallel hard disk. take a look at the 40MHz+ AVRs/PICs, or something ARM-based. However, there's not much hope of using USB or SATA unless you have access to FPGA facilities. ch424
err, the PIC18F4550 does have on-chip USB possibilities... pity it's a PDIP40 chip, a.k.a. pretty damn big. I guess it wouldn't be easy, but you can at least connect CF cards to a PIC chip, and most likely also ATA hard-drives, but an USB-MSD i'm not sure of...
You cannot use the 18F4550 (or the 18F2550) as a USB host. As a USB/UMS client, you can only manage 440kb/sec, which is pants.
then I can't think of anything but the ARM chips to do this sort of stuff... whatever the solution might be, it'll be difficult
You can do (slow) usb with almost anything. Just do all the work in software. Actually, you don't need usb at all. You want to go from a hard drive (pata is a good idea) to a SPI interface. You just need something with a lot of pins. I would imagine you could probably do it with a pic16f877a (or similar), if you're good with software.
440kb/sec is probably enough for an mp4 player, how many people listen to music more than 192kbps? I would say this is possible, but extremely difficult, good luck if you give it a go, but I'm not too hopeful.
I was making the point that in client mode, it can only manage 440kb/sec, so as a host there's absolutely no hope.
