USB device stack

Dependents:   mbed-mX-USB-TEST1 USBMSD_SD_HID_HelloWorld HidTest MIDI_usb_bridge ... more

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USBMSD Class Reference

USBMSD Class Reference

USBMSD class: generic class in order to use all kinds of blocks storage chip. More...

#include <USBMSD.h>

Inherits USBDevice.

Public Member Functions

 USBMSD (uint16_t vendor_id=0x0703, uint16_t product_id=0x0104, uint16_t product_release=0x0001)
bool connect (bool blocking=true)
 Connect the USB MSD device.
void disconnect ()
 Disconnect the USB MSD device.

Detailed Description

USBMSD class: generic class in order to use all kinds of blocks storage chip.


The USBMSD implements the MSD protocol. It permits to access a memory chip (flash, sdcard,...) from a computer over USB. But this class doesn't work standalone, you need to subclass this class and define virtual functions which are called in USBMSD.

How to use this class with your chip ?

You have to inherit and define some pure virtual functions (mandatory step):

  • virtual int disk_read(char * data, int block): function to read a block
  • virtual int disk_write(const char * data, int block): function to write a block
  • virtual int disk_initialize(): function to initialize the memory
  • virtual int disk_sectors(): return the number of blocks
  • virtual int disk_size(): return the memory size
  • virtual int disk_status(): return the status of the storage chip (0: OK, 1: not initialized, 2: no medium in the drive, 4: write protection)

All functions names are compatible with the fat filesystem library. So you can imagine using your own class with USBMSD and the fat filesystem library in the same program. Just be careful because there are two different parts which will access the sd card. You can do a master/slave system using the disk_status method.

Once these functions defined, you can call connect() (at the end of the constructor of your class for instance) of USBMSD to connect your mass storage device. connect() will first call disk_status() to test the status of the disk. If disk_status() returns 1 (disk not initialized), then disk_initialize() is called. After this step, connect() will collect information such as the number of blocks and the memory size.

Definition at line 58 of file USBMSD.h.

Constructor & Destructor Documentation

USBMSD ( uint16_t  vendor_id = 0x0703,
uint16_t  product_id = 0x0104,
uint16_t  product_release = 0x0001 


vendor_idYour vendor_id
product_idYour product_id
product_releaseYour preoduct_release

Definition at line 66 of file USBMSD.cpp.

~USBMSD (  )


Definition at line 73 of file USBMSD.cpp.

Member Function Documentation

bool connect ( bool  blocking = true )

Connect the USB MSD device.

Establish disk initialization before really connect the device.

blockingif not configured
true if successful

Definition at line 106 of file USBMSD.cpp.

void disconnect ( void   )

Disconnect the USB MSD device.

Definition at line 137 of file USBMSD.cpp.