Merge pull request #25 from FrankBoesing/patch-1

Fix read-after-write

SerialFlashChip.cpp

 			SPI.transfer(*p++);
 		} while (--pagelen > 0);
 		CSRELEASE();
-		busy = 1;
+		busy = 4;
 		SPI.endTransaction();
 	} while (len > 0);
 }