diff --git a/app/src/main/java/com/example/medilightv2android/ble/BleManager.kt b/app/src/main/java/com/example/medilightv2android/ble/BleManager.kt
index 1d71c6c..bd0f53f 100644
--- a/app/src/main/java/com/example/medilightv2android/ble/BleManager.kt
+++ b/app/src/main/java/com/example/medilightv2android/ble/BleManager.kt
@@ -1104,6 +1104,8 @@ class BleManager private constructor(private val context: Context) {
 
     private fun processReceivedData(data: ByteArray) {
         lastRxTimestamp = System.currentTimeMillis()
+        // Raw BLE capture (디버그 — 사용자가 토글로 enable 했을 때만 writes)
+        com.example.medilightv2android.services.RawBleLogger.write(data)
         val prefix = String(data, 0, minOf(4, data.size), Charsets.US_ASCII)
         logd { "Received: $prefix (${data.size} bytes)" }
         when (prefix) {
diff --git a/app/src/main/java/com/example/medilightv2android/services/RawBleLogger.kt b/app/src/main/java/com/example/medilightv2android/services/RawBleLogger.kt
new file mode 100644
index 0000000..8ab12d0
--- /dev/null
+++ b/app/src/main/java/com/example/medilightv2android/services/RawBleLogger.kt
@@ -0,0 +1,94 @@
+/*
+ * RawBleLogger — 모든 BLE notification 의 raw bytes 를 시간순으로 파일로 dump.
+ *
+ * 용도: IMU FSR / packet 구조 / loss 진단. JSON 가공 거치기 전 원본 그대로 저장.
+ *
+ * 파일: Downloads/VesiScan_RawBLE/yyyy-MM-dd_HHmmss_raw.log
+ * 포맷 (한 줄당 한 notification):
+ *   HH:mm:ss.SSS dir=RX prefix=rim len=188 hex=72 69 6D 3A 00 0F ...
+ *
+ * 사용: startCapture() / stopCapture() 토글. 활성화 시 BleManager.processReceivedData
+ * 가 매 notification 마다 write() 호출.
+ */
+package com.example.medilightv2android.services
+
+import android.os.Environment
+import java.io.File
+import java.io.FileWriter
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.concurrent.atomic.AtomicBoolean
+
+object RawBleLogger {
+
+    private val sessionFmt = SimpleDateFormat("yyyy-MM-dd_HHmmss", Locale.US)
+    private val timeFmt = SimpleDateFormat("HH:mm:ss.SSS", Locale.US)
+    private val capturing = AtomicBoolean(false)
+    @Volatile private var sessionFile: File? = null
+    @Volatile private var packetCount: Int = 0
+
+    val isCapturing: Boolean get() = capturing.get()
+    val currentFile: File? get() = sessionFile
+    val count: Int get() = packetCount
+
+    private fun getDir(): File {
+        val dir = File(
+            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
+            "VesiScan_RawBLE"
+        )
+        if (!dir.exists()) dir.mkdirs()
+        return dir
+    }
+
+    /** 새 파일 만들고 capture 시작. 이미 capturing 중이면 stop 후 새로 시작. */
+    fun startCapture(): File {
+        if (capturing.get()) stopCapture()
+        val f = File(getDir(), "${sessionFmt.format(Date())}_raw.log")
+        try {
+            FileWriter(f, false).buffered().use { w ->
+                w.write("# RawBleLogger session — started ${timeFmt.format(Date())}")
+                w.newLine()
+                w.write("# Format: HH:mm:ss.SSS dir=RX prefix=XXX len=N hex=AA BB ...")
+                w.newLine()
+            }
+        } catch (_: Exception) {}
+        sessionFile = f
+        packetCount = 0
+        capturing.set(true)
+        return f
+    }
+
+    fun stopCapture(): File? {
+        if (!capturing.get()) return sessionFile
+        val f = sessionFile
+        try {
+            if (f != null) {
+                FileWriter(f, true).buffered().use { w ->
+                    w.write("# stopped ${timeFmt.format(Date())} — $packetCount packets")
+                    w.newLine()
+                }
+            }
+        } catch (_: Exception) {}
+        capturing.set(false)
+        return f
+    }
+
+    /** BleManager 가 매 notification 받을 때마다 호출. capturing 아니면 즉시 return. */
+    fun write(data: ByteArray) {
+        if (!capturing.get()) return
+        val f = sessionFile ?: return
+        try {
+            val ts = timeFmt.format(Date())
+            val prefix = if (data.size >= 4)
+                String(data, 0, 4, Charsets.US_ASCII).replace(Regex("[^\\x20-\\x7E]"), "?")
+                else "?"
+            val hex = data.joinToString(" ") { "%02X".format(it) }
+            FileWriter(f, true).buffered().use { w ->
+                w.write("$ts dir=RX prefix=$prefix len=${data.size} hex=$hex")
+                w.newLine()
+            }
+            packetCount++
+        } catch (_: Exception) {}
+    }
+}
diff --git a/app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt b/app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt
index b3985c5..62a657f 100644
--- a/app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt
+++ b/app/src/main/java/com/example/medilightv2android/ui/views/monitoring/PiezoMonitoringView.kt
@@ -979,6 +979,38 @@ fun PiezoMonitoringView(appState: AppState) {
             }
             Spacer(modifier = Modifier.width(8.dp))
 
+            // Raw BLE capture toggle — IMU/packet 디버그용 (Downloads/VesiScan_RawBLE/)
+            var rawBleCapturing by remember {
+                mutableStateOf(com.example.medilightv2android.services.RawBleLogger.isCapturing)
+            }
+            IconButton(
+                onClick = {
+                    if (rawBleCapturing) {
+                        val f = com.example.medilightv2android.services.RawBleLogger.stopCapture()
+                        val n = com.example.medilightv2android.services.RawBleLogger.count
+                        rawBleCapturing = false
+                        android.widget.Toast.makeText(context,
+                            "Raw BLE: $n packets saved to ${f?.name}",
+                            android.widget.Toast.LENGTH_LONG).show()
+                    } else {
+                        val f = com.example.medilightv2android.services.RawBleLogger.startCapture()
+                        rawBleCapturing = true
+                        android.widget.Toast.makeText(context,
+                            "Raw BLE capture started → ${f.name}",
+                            android.widget.Toast.LENGTH_SHORT).show()
+                    }
+                },
+                modifier = Modifier.size(28.dp)
+            ) {
+                Icon(
+                    if (rawBleCapturing) Icons.Default.RadioButtonChecked else Icons.Default.FiberManualRecord,
+                    contentDescription = if (rawBleCapturing) "Stop raw BLE capture" else "Start raw BLE capture",
+                    tint = if (rawBleCapturing) Color.Red else Color.Gray.copy(alpha = 0.5f),
+                    modifier = Modifier.size(20.dp)
+                )
+            }
+            Spacer(modifier = Modifier.width(4.dp))
+
             // Catheter count (탭하면 추가 팝업)
             var showAddCatheter by remember { mutableStateOf(false) }
             val cathCount = appState.catheterCount.intValue