how do i access RAM on a USB flash drive ?

Question

hello smart people, nerds, wiz-kids and enthusiasts

i need the protocol to access memory on a USB stick

i know that i send address, data and control information to access a location in flash ram, but what is the format

address first (LSB to MSB), data second, then a read or write control byte third

i noticed that as something becomes worth more on the market, it becomes harder to get concise and comprehensive technical data

the PIC18F4455 microcontroller has a 430 page data sheet. usefull for actually designing operational circuits

3 pages for a USB stick? useless if i want to hook it to my PIC development board

the USB protocol aint a problem. theres tons of data on that

all answers welcome

peter

when in doubt, ask

johnbeetem · Accepted Answer

I've never played with a USB Flash Drive at the USB protocol level, but my understanding is that a USB Flash Drive is handled as a USB Mass Storage device, with the actual access to the memory chip handled through a microcontroller in the Flash Drive. The uC takes care of things like wear leveling so that the flash memory writes are distributed across the chip instead of wearing out one region.

For general information on USB Flash Drives, try Wikipedia: http://en.wikipedia.org/wiki/USB_Flash_drive

For specific information on USB device protocols, try USB.org: http://www.usb.org/developers/docs/devclass_docs/

TaylorTronics · Answer

thanks john

i have found that usb ram is accessed using the usb mass memory protocol

simple realy, untill you read it

i found the answer at edaboard.com

in microcontrollers, with 255,000 views

definatly go thier for an answer, in fact 5 answers

you are on the nail

peter taylor

the sun does revolve around the earth

vmate · Answer

I'd use an SD card instead, they support SPI for communication, so they are much easier to interface with. Also, the microcontroller you mentioned only supports USB device as far as I can tell, and you'd need USB host capabilities. You can bit bang it, but that's even harder, and really slow.

how do i access RAM on a USB flash drive ?

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