diff --git a/Firmware/platformio.ini b/Firmware/platformio.ini
index 3f8713d..7f2e8ae 100644
--- a/Firmware/platformio.ini
+++ b/Firmware/platformio.ini
@@ -4,15 +4,11 @@
 ; https://docs.platformio.org/page/projectconf.html
 
 [platformio]
-default_envs = release
+default_envs = debug
 libdeps_dir = depends
 
 [env]
-platform = atmelavr
-
-; solves avr-debugger issue https://github.com/jdolinay/avr_debug/issues/19
-platform_packages =   
-  toolchain-atmelavr@~1.70300.0   ; use GCC AVR 7.3.0+
+platform = atmelavr @ ^3.3.0
 
 board = emgdmm_v3
 monitor_speed = 9600
@@ -25,21 +21,23 @@ lib_deps =
 [env:release] ; for flash via bootloader
 ; keep defaults, see board definitions for programming support
 
+
 [env:debug] ; for debugging using avr-stub, see documentation
 build_type = debug
 build_flags = 
     -D DEBUG 
-    -D GDBSTUB 
+    -D GDBSTUB ; program should disable any own UART use if this is defined
     -D AVR8_BREAKPOINT_MODE=2
-    ;-D __AVR_ATmega1284P__      ; required by avr8-stub.c
 
 debug_tool = avr-stub
+debug_port = /dev/ttyUSB0 ; TODO: this should be infered automagically
 
-; GDB stub implementation
+; add GDB stub implementation
 lib_deps =
     ${env.lib_deps}   
     jdolinay/avr-debugger @ ^1.3
 
+
 [env:jtag] ; for JTAG bootloader flashing and potentialy debugging once supported
 build_type = debug
 build_flags =