[ES] Added initialization of SD library

Signed-óff-by: Jim Martens <github@2martens.de>

es/blatt6/uebung6-1/uebung6-1.ino

@@ -3,6 +3,7 @@
 
 // pins
 int slaveSelectPin = 10;
+int SDslaveSelectPin = 4;
 int rstPin = 6;
 int dcPin = 5;
 
@@ -124,6 +125,9 @@ void setup()
   SPI.begin(slaveSelectPin);
   SPI.setClockDivider(slaveSelectPin, divider);
 
+  // initialize SD
+  SD.begin(SDslaveSelectPin);
+
   // initialize pins
   pinMode(dcPin, OUTPUT);
   pinMode(rstPin, OUTPUT);