diff --git a/roles/private.nix b/roles/private.nix
index 0776b19..a3fea9f 100644
--- a/roles/private.nix
+++ b/roles/private.nix
@@ -4,17 +4,27 @@ let
   unstable = import <nixos-unstable> {};
 in {
   environment.systemPackages = with pkgs; [
+    # embedded
     arduino
     avrdude
+    gcc-arm-embedded
+    openocd
     pkgsCross.avr.avrlibc
-    pkgsCross.avr.libcCross
-    pkgsCross.avr.buildPackages.gcc8
     pkgsCross.avr.buildPackages.binutils
-    unstable.cura
+    pkgsCross.avr.buildPackages.gcc8
+    pkgsCross.avr.libcCross
+
+    cura
     openscad
     kicad
   ];
 
+  # stm32 debugger
+  users.extraGroups.plugdev = { };
+  users.extraUsers.stefan.extraGroups = [ "plugdev" "dialout" ];
+  services.udev.packages = [ pkgs.openocd ];
+
+
   fileSystems."/mnt/nfs" = {
     device = "10.1.20.29:/srv/nfs";
     fsType = "nfs";