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+The Flash Driver
+================
+
+Flash is a re-programmable memory that retains program and data
+storage even with power off.
+
+User can write or read several bytes from any valid address in a flash.
+
+As to the erase/lock/unlock command, the input parameter of address should
+be a bytes address aligned with the page start, otherwise, the command will fail
+to be executed. At the meantime, the number of pages that can be locked or unlocked
+at once depends on region size of the flash. User can get the real number
+from the function return value which could be different for the different devices.
+
+Features
+--------
+
+* Initialization/de-initialization
+* Writing/Reading bytes
+* Locking/Unlocking/Erasing pages
+* Notifications about errors or being ready for a new command
+
+Applications
+------------
+
+* Mini disk which can retain program and data storage
+* Boot loader
+* Non volatile storage
+
+Dependencies
+------------
+
+The peripheral which controls a re-programmable flash memory.
+
+Concurrency
+-----------
+
+N/A
+
+Limitations
+-----------
+
+User should pay attention to set a proper stack size in their application,
+since the driver manages a temporary buffer in stack to cache unchanged data
+when calling flash write and erase function.
+Due to flash memory architecture of SAMD21/D20/L21/L22/C20/C21/D09/D10/D11/R21,
+write operation erazes row content before each write.
+
+Known issues and workarounds
+----------------------------
+
+N/A