USB flash drive to memory card

[blackridinghood]

I want to convert USB flash drive to a memory card that can be inserted in devices that have an MMC ports. This is like mobidapter. I've read that I need a USB host before to work with USB devices, but what if I'll connect it to a phone? Please suggest the cheap ones components? Thanks in advance..:lol::lol:

 

[seadolphine2000]

The USB drives have totally different protocols than regular memory cards. Memory cards can be interfaced using simple "SPI" protocol but, USB drives use totally different protocols. USB devices require host controllers (Master device that will initiate the communication with the slave device) then, you will implement a driver for that flash drive before you can communicate with it.
To do so, you need a powerful microcontroller and, a very good programming knowledge.

 

[embedsys]

just go through the IC VUB300.

 

[blackridinghood]

just go through the IC VUB300.

Is this the IC used for mobidapter?

 

[seadolphine2000]

I think this IC works the other way, that is interfacing SD cards or SDIO to devices those have USB ports but not SD slots.
From what I understood from blackridinghood, he needs a solution to interface his USB flash drive to his phone via the SD or MMC card slot.
Please correct me if I'm wrong.

 

[FvM]

I don't expect, that a bridge chip with the requested functionality exists. As said, the other way around is quite common, you can buy the adpaters at a computer store next door. So your design idea involves an USB host and a MMC card emulation. SPI slave would be almost easy, but you can't be sure that the device isn't using the generic MMC interface mode. Fortunately you can restrict the clock speed in the emulated CSD (card specific data) register. A minimum of 400 kBit/s must be supported in initial MMC identification mode. So all in all, it can be most likely done with a uP with USB host functionality, e.g. PIC24, ATmega or ARM7.

 

[blackridinghood]

It goes like this:

USB flash drive ---->>>[Circuit that convert USB flash drive to MMC (like mini sd)] ------->>> Phone that supports mini sd

Doesn't a cellphone easily gets the data in the USB when connected to the data lines of the mmc port of the cellphone? But I guess it wasn't that easy. arrgghh confused.. What pic24 can you recommend? It has a USB host right?

Thank you so much for replying guys..

 

[FvM]

PIC24FJxxGByy comes with USB host capability.

 

[blackridinghood]

Is Pic24fj64gb002 is ok? This is w/ nano watt technology(XLP), is this the same w/ others that don't have XLP?

 

[FvM]

Pic24fj64gb002 also has the host capability, if it's sufficient for your application can be decided, when you know about the code size. You can refer to the USB Host - Mass Storage demo applications downloadable from Microchip to get an idea about the USB code size.

 

[seadolphine2000]

Yes, it's USB V2.0 OTG compliant
PIC24FJ64GB002

 

[embedsys]

I also agree with FvM. if your need is like mobidapter. you can go for PIC24FJ64GB002 itself. it is having USB Host. All the best.