diff --git a/builder/frameworks/arduino/arduino.py b/builder/frameworks/arduino/arduino.py
new file mode 100644
index 0000000..065e58e
--- /dev/null
+++ b/builder/frameworks/arduino/arduino.py
@@ -0,0 +1 @@
+# ToDo: readout core and call correct builder script (e.g., mbed-core/arduino-core-mbed.py)
\ No newline at end of file
diff --git a/platform.json b/platform.json
index d50178c..11d90ee 100644
--- a/platform.json
+++ b/platform.json
@@ -22,7 +22,7 @@
   "frameworks": {
     "arduino": {
       "package": "framework-arduino-mbed",
-      "script": "builder/frameworks/arduino/mbed-core/arduino-core-mbed.py"
+      "script": "builder/frameworks/arduino/arduino.py"
     }
   },
   "packages": {
@@ -37,6 +37,12 @@
       "owner": "platformio",
       "version": "~2.1.0"
     },
+    "framework-arduino-pico-earlephilhower": {
+      "type": "framework",
+      "optional": true,
+      "owner": "maxgerhardt",
+      "version": "~1.10902.0"
+    },
     "tool-rp2040tools": {
       "type": "uploader",
       "owner": "platformio",
diff --git a/platform.py b/platform.py
index c4e29da..03ca245 100644
--- a/platform.py
+++ b/platform.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import sys
 import copy
 import platform
 
@@ -24,6 +25,24 @@ class RaspberrypiPlatform(PlatformBase):
         return True
 
     def configure_default_packages(self, variables, targets):
+        # configure arduino core package. 
+        # select the right one based on the build.core, disable other one.
+        board = variables.get("board")
+        board_config = self.board_config(board)
+        build_core = variables.get(
+            "board_build.core", board_config.get("build.core", "arduino"))
+
+        frameworks = variables.get("pioframework", [])
+        if "arduino" in frameworks:
+            if build_core == "arduino":
+                self.frameworks["arduino"]["package"] = "framework-arduino-mbed"
+                self.packages["framework-arduino-pico-earlephilhower"]["optional"] = True
+            elif build_core == "earlephilhower":
+                self.frameworks["arduino"]["package"] = "framework-arduino-pico-earlephilhower"
+                self.packages["framework-arduino-mbed"]["optional"] = True
+            else: 
+                sys.stderr.write("Error! Unknown build.core value '%s'. Don't know which Arduino core package to use." % build_core)
+
         # configure J-LINK tool
         jlink_conds = [
             "jlink" in variables.get(option, "")