diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..da56c3f
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "stm-firmware/shellmatta"]
+	path = stm-firmware/shellmatta
+	url = https://git.shimatta.net/shimatta/shellmatta
diff --git a/stm-firmware/shellmatta b/stm-firmware/shellmatta
new file mode 160000
index 0000000..ad60578
--- /dev/null
+++ b/stm-firmware/shellmatta
@@ -0,0 +1 @@
+Subproject commit ad60578aabafafe35348ed8f791e422f68bf6c18