diff --git a/Test.xml b/Test.xml
index 7273dee..26ac17c 100644
--- a/Test.xml
+++ b/Test.xml
@@ -7,7 +7,7 @@
         </Port>
     </Device>
     <Device name="PWM_example">
-        <Port protocol="PWM" frequency="2">
+        <Port protocol="PWM" frequency="2" buffer_size="1000">
             <Pin>GPIO_10</Pin>
         </Port>
     </Device>
diff --git a/config.xsd b/config.xsd
index d8adb11..f93305d 100644
--- a/config.xsd
+++ b/config.xsd
@@ -27,6 +27,13 @@
         </xs:restriction>
     </xs:simpleType>
 
+    <!-- available buffer sizes -->
+    <xs:simpleType name="BufferSizeType">
+        <xs:restriction base="xs:integer">
+            <xs:minInclusive value="1"/>
+            <xs:maxInclusive value="10000"/>
+        </xs:restriction>
+    </xs:simpleType>
 
     <!-- available Pins -->
     <xs:simpleType name="Pin">
@@ -101,6 +108,7 @@
             </xs:sequence>
             <xs:attribute name="protocol" type="ProtocolType" use="required"/>
             <xs:attribute name="frequency" type="FrequencyType" use="optional"/>
+            <xs:attribute name="buffer_size" type="BufferSizeType" use="optional"/>
         </xs:complexType>
     </xs:element>
 </xs:schema>
\ No newline at end of file