+            try:
+                self._i2c.writeto(self._dev_addr, buffer=data_bytes)
+            except OSError as error:
+                if error.errno == 121:
+                    raise RuntimeError(
+                        f"I2C write error to 0x{self._dev_addr:02x}"
+                    ) from error
+                raise error
+
+    def _free(self) -> bool:
+        """Attempt to free the bus and return False if busy"""
+        if not self._i2c.try_lock():
+            return False
+        self._i2c.unlock()
+        return True
+
+    def _begin_transaction(self) -> bool:
+        """Lock the bus before sending data."""
+        return self._i2c.try_lock()