diff --git a/.gitignore b/.gitignore
index 0fc0096..71d7392 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,6 @@
 *.FCStd
 *.FCBak
-*.3mf
\ No newline at end of file
+*.3mf
+*.pio
+*.claude
+*.vscode
\ No newline at end of file
diff --git a/platformio.ini b/platformio.ini
new file mode 100644
index 0000000..53a49ff
--- /dev/null
+++ b/platformio.ini
@@ -0,0 +1,38 @@
+; ── PlatformIO project configuration ─────────────────────────────────────────
+; Board  : Seeed XIAO nRF52840 Sense
+; Core   : Adafruit nRF52 Arduino (via Seeed platform-seeedboards)
+; Flash  : adafruit-nrfutil over USB serial (same as Arduino IDE)
+;
+; First-time setup:
+;   pip install adafruit-nrfutil          <- upload tool (once, globally)
+;   pio run -t upload                     <- build + flash
+; ──────────────────────────────────────────────────────────────────────────────
+
+[env:xiao_nrf52840_sense]
+platform  = https://github.com/Seeed-Studio/platform-seeedboards.git
+board     = seeed-xiao-afruitnrf52-nrf52840
+framework = arduino
+
+; ── Upload ────────────────────────────────────────────────────────────────────
+; The XIAO uses a UF2 bootloader that accepts firmware via adafruit-nrfutil.
+; Double-tap the reset button to enter bootloader (red LED pulses) before
+; flashing if the board isn't auto-reset by the tool.
+upload_protocol = nrfutil
+upload_speed    = 115200
+; Uncomment and set the correct port if auto-detect fails:
+; upload_port   = COM3
+
+; ── Build flags ───────────────────────────────────────────────────────────────
+build_flags =
+    -DARDUINO_Seeed_XIAO_nRF52840_Sense
+    -DNRF52840_XXAA
+
+; ── Libraries ─────────────────────────────────────────────────────────────────
+; bluefruit.h, Adafruit_LittleFS.h, InternalFileSystem.h are bundled with
+; the Adafruit nRF52 core and do NOT need to be listed here.
+; Only external libraries are listed:
+lib_deps =
+    Seeed-Studio/Seeed Arduino LSM6DS3 @ ^2.0.3
+
+; ── Serial monitor ────────────────────────────────────────────────────────────
+monitor_speed = 115200