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i am working on a project that requires me to read the filenames from a usb flash drive/pen drive. I could use a raspberry pi and be done with but the power requirements for a portable system is limiting. a friend recommend that i look into usb host and a microcontroller to go thru and read directory listing. i can't seem to find the best way of doing this.

Project requirements:

  1. Portable
  2. Power using a coin cell battery.
  3. 1 usb port
  4. 3.5in lcd display
  5. Read file and folder names.

What is the best way and/or are there tutorials?

Any help is greatly appreciated and pardon my grammar.

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closed as too broad by DoxyLover, duskwuff, Voltage Spike, Wesley Lee, Dmitry Grigoryev Mar 17 '17 at 8:45

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ "usb flash drive/pen drive" "Power using a coin cell battery" Nope. \$\endgroup\$ – Ignacio Vazquez-Abrams Mar 17 '17 at 4:59
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    \$\begingroup\$ Your requirements are simply unrealistic. No LCD, USB controller or pen drive alone will work from a coin cell battery. Just use a Rapberry pi and be done with it. \$\endgroup\$ – Dmitry Grigoryev Mar 17 '17 at 8:45
  • \$\begingroup\$ For the USB part, have a look at the CH375 chips and support boards ("u-disk"). They allow high-level access to FAT USB mass storage devices via SPI. This can be used with any controller and, for a few bucks, does all the USB plus filesystem stuff for you. \$\endgroup\$ – JimmyB Mar 17 '17 at 14:08
  • \$\begingroup\$ Sorry, the part with FAT support is the CH376. \$\endgroup\$ – JimmyB Mar 17 '17 at 14:18
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You need to provide at least 100 to 200 milliamperes at 5 volts to the USB flash for it to work. There's no way you could ever accomplish that from a coin cell battery.

That said, if you can find the way to get enough power, there's several microcontrollers that can do the job. You might grab a hold of Jan Axelson's book "USB Mass Storage" to get an idea how it's basically done.

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