diff --git a/ports/zephyr-cp/cptools/tests/test_zephyr2cp.py b/ports/zephyr-cp/cptools/tests/test_zephyr2cp.py
index 556aec0cccb..403bd2fd94e 100644
--- a/ports/zephyr-cp/cptools/tests/test_zephyr2cp.py
+++ b/ports/zephyr-cp/cptools/tests/test_zephyr2cp.py
@@ -24,6 +24,7 @@
     MINIMUM_RAM_SIZE,
     add_toml_pin_names,
     _toml_status_pin,
+    _dynamically_routable,
 )
 
 
@@ -796,3 +797,50 @@ def test_absent_key_is_none(self):
     def test_unknown_name_raises(self):
         with pytest.raises(RuntimeError, match="STATUS_NEOPIXEL = 'NOPE' is not a board pin name"):
             _toml_status_pin({"STATUS_NEOPIXEL": "NOPE"}, self.BOARD_NAMES, "STATUS_NEOPIXEL")
+
+
+class TestDynamicallyRoutable:
+    """Test suite for _dynamically_routable function."""
+
+    def _bus(self, group):
+        dts = f"""
+/dts-v1/;
+
+/ {{
+    pinctrl {{
+        bus_default: bus_default {{
+            group1 {{
+                {group}
+            }};
+        }};
+    }};
+
+    bus: bus@1000 {{
+        reg = <0x1000 0x100>;
+        pinctrl-0 = <&bus_default>;
+        pinctrl-names = "default";
+    }};
+}};
+"""
+        return parse_dts_string(dts).label2node["bus"]
+
+    def test_nrf_all_disconnected(self):
+        assert _dynamically_routable(self._bus("psels = <0x0b0001ff 0x0c0001ff>;"))
+
+    def test_nrf_connected(self):
+        assert not _dynamically_routable(self._bus("psels = <0x0b00000a 0x0c0001ff>;"))
+
+    def test_pinmux_without_psels(self):
+        assert not _dynamically_routable(self._bus("pinmux = <0x1234 0x5678>;"))
+
+    def test_no_pinctrl(self):
+        dts = """
+/dts-v1/;
+
+/ {
+    bus: bus@1000 {
+        reg = <0x1000 0x100>;
+    };
+};
+"""
+        assert not _dynamically_routable(parse_dts_string(dts).label2node["bus"])
diff --git a/ports/zephyr-cp/cptools/zephyr2cp.py b/ports/zephyr-cp/cptools/zephyr2cp.py
index 660b263262f..ee813ba4883 100644
--- a/ports/zephyr-cp/cptools/zephyr2cp.py
+++ b/ports/zephyr-cp/cptools/zephyr2cp.py
@@ -550,6 +550,17 @@ def _pinctrl_default_psels(node):
     return psels
 
 
+def _dynamically_routable(node):
+    """Return True when every nRF psel in the node's default pinctrl state is
+    disconnected. Pinctrl states on other SoCs have no psels, so their buses
+    keep the pins the devicetree gives them.
+    """
+    psels = _pinctrl_default_psels(node)
+    return bool(psels) and all(
+        (value & NRF_PIN_FIELD_MASK) == NRF_PIN_FIELD_MASK for value in psels
+    )
+
+
 def _populate_input_key_names():
     header = (
         pathlib.Path(__file__).parent.parent
@@ -1300,11 +1311,7 @@ def zephyr_dts_to_cp_board(board_id, portdir, builddir, zephyrbuilddir, mpconfig
     iobroker_labels = set()
     for driver in BUSIO_CLASSES:
         for labels in active_zephyr_devices.get(driver, []):
-            node = device_tree.label2node[labels[0]]
-            psels = _pinctrl_default_psels(node)
-            if psels is not None and all(
-                (value & NRF_PIN_FIELD_MASK) == NRF_PIN_FIELD_MASK for value in psels
-            ):
+            if _dynamically_routable(device_tree.label2node[labels[0]]):
                 iobroker_labels.add(labels[0])
 
     zephyr_binding_headers = []