added platformio configuration

Author: f-reiling

.gitignore

@@ -0,0 +1,6 @@
+.cache
+.pio
+.vscode/.browse.c_cpp.db*
+.vscode/c_cpp_properties.json
+.vscode/launch.json
+.vscode/ipch

platformio.ini

@@ -0,0 +1,24 @@
+[platformio]
+description                 = Modbus RTU TCP gateway
+src_dir                     = arduino-modbus-rtu-tcp-gateway
+lib_dir                     = lib/default
+;boards_dir                  = boards
+build_cache_dir             = .cache
+
+[env]
+platform = atmelavr
+framework = arduino
+board = nanoatmega328
+
+lib_deps = arduino-libraries/Ethernet@^2.0.2
+           rlogiacco/CircularBuffer@^1.3.3
+           jandrassy/StreamLib
+
+[env:nanoatmega328new]
+board = nanoatmega328new
+
+[env:nanoatmega328]
+board = nanoatmega328
+
+[env:arduinouno]
+board = uno