diff --git a/y2019/vision/constants.h b/y2019/vision/constants.h
index cc6775e..3f07f87 100644
--- a/y2019/vision/constants.h
+++ b/y2019/vision/constants.h
@@ -79,7 +79,26 @@
 
 const CameraCalibration *GetCamera(int camera_id);
 
-void DumpCameraConstants(int camera_id, const CameraCalibration &value);
+// Serial number of the teensy for each robot.
+constexpr uint32_t CodeBotTeensyId() { return 0xffff322e; }
+
+// Get the IDs of the cameras in each port for a particular teensy board.
+// inlined so that we don't have to deal with including it in the autogenerated
+// constants.cc.
+inline std::array<int, 5> CameraSerialNumbers(uint32_t processor_id) {
+  switch (processor_id) {
+    case CodeBotTeensyId():
+      return {{0, 0, 0, 16, 19}};
+    default:
+      return {{0, 0, 0, 0, 0}};
+  }
+}
+
+// Rewrites constants.cc, adding camera calibration constants for the camera_id
+// specified. If camera_id is less than zero, just rewrites the file without
+// changing anything.
+void DumpCameraConstants(const char *fname, int camera_id,
+                         const CameraCalibration &value);
 
 }  // namespace vision
 }  // namespace y2019