diff --git a/SETUP_REQUIRED.txt b/SETUP_REQUIRED.txt
new file mode 100644
index 0000000..d73a7b7
--- /dev/null
+++ b/SETUP_REQUIRED.txt
@@ -0,0 +1,13 @@
+20260425 ChatGPT
+$Header$
+
+This project requires submodules.
+
+Run:
+
+    git submodule update --init --recursive
+
+before building, or compilation will fail with missing headers such as:
+
+    Boards.h
+    SensorQMC6310.hpp