- * Write program memory.
- * Write \a size bytes from buffer \a _buf to file \a fd
- * \note Write operations are buffered.
+ * Write \a _buf in data flash memory
+ *
+ * \note For write \a _buf in data flash memory, we must
+ * before write in buffer data flash memory, and at end of write,
+ * we put page in data flash main memory. If we write in two
+ * different page, we put in main memory current page and reload
+ * page witch we want write.
+ *
+ * \return the number of bytes write.