diff --git a/.gitea/workflows/build.yml b/.gitea/workflows/build.yml
new file mode 100644
index 0000000..9000b86
--- /dev/null
+++ b/.gitea/workflows/build.yml
@@ -0,0 +1,36 @@
+name: Build Firmware
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build stm32-teslacharger
+    runs-on: fedora
+
+    steps:
+      - name: Checkout with submodules
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+          fetch-depth: 0
+
+      - name: Build libopencm3
+        run: make get-deps
+
+      - name: Build firmware
+        run: make directories && make images -j$(nproc)
+
+      - name: Show binary size
+        run: ls -lh stm32_charger.bin
+
+      - name: Upload binary
+        uses: actions/upload-artifact@v3
+        with:
+          name: stm32-teslacharger-${{ github.sha }}
+          path: stm32_charger.bin
+          retention-days: 30
diff --git a/.gitmodules b/.gitmodules
index 9d3d04c..e53231c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,6 @@
 [submodule "libopencm3"]
 	path = libopencm3
-	url = git@github.com:jsphuebner/libopencm3.git
+	url = https://github.com/jsphuebner/libopencm3.git
 [submodule "libopeninv"]
 	path = libopeninv
-	url = git@github.com:jsphuebner/libopeninv.git
+	url = https://github.com/jsphuebner/libopeninv.git
diff --git a/src/chargercan.cpp b/src/chargercan.cpp
index bd15864..e20d901 100644
--- a/src/chargercan.cpp
+++ b/src/chargercan.cpp
@@ -99,4 +99,7 @@ void ChargerCAN::MapMessages(CanMap* can)
    can->AddSend(Param::udc, 0x109, 8, 16, 1);
    can->AddSend(Param::idc, 0x109, 24, 16, 1);
    can->AddSend(Param::opmode, 0x109, 40, 3, 5); //Set charging and connlock at once
+
+   /***** Auxiliary TX *****/
+   can->AddSend(Param::uaux, 0x210, 0, 8, 10); //12V aux battery: byte 0, gain=10 (0.1V/decivolts, SKUDAK-448)
 }