diff --git a/android/app/src/main/java/com/eddy/atomrelay/EspFlasher.kt b/android/app/src/main/java/com/eddy/atomrelay/EspFlasher.kt
new file mode 100644
index 0000000..03e3eef
--- /dev/null
+++ b/android/app/src/main/java/com/eddy/atomrelay/EspFlasher.kt
@@ -0,0 +1,134 @@
+package com.eddy.atomrelay
+
+import android.content.Context
+import android.hardware.usb.UsbConstants
+import android.hardware.usb.UsbDevice
+import android.hardware.usb.UsbManager
+import android.os.Handler
+import android.os.Looper
+import android.util.Log
+import org.dkaukov.esp32.core.EspFlasherApi
+import org.dkaukov.esp32.io.ProgressCallback
+import java.io.IOException
+
+class EspFlasher(private val context: Context) {
+
+    companion object {
+        private const val TAG = "EspFlasher"
+    }
+
+    interface FlashCallback {
+        fun onProgress(percent: Int, message: String)
+        fun onComplete()
+        fun onError(message: String)
+    }
+
+    private val handler = Handler(Looper.getMainLooper())
+
+    fun flashDevice(usbManager: UsbManager, device: UsbDevice, callback: FlashCallback) {
+        Thread {
+            try {
+                doFlash(usbManager, device, callback)
+            } catch (e: Exception) {
+                Log.e(TAG, "Flash failed", e)
+                handler.post { callback.onError(e.message ?: "Onbekende fout") }
+            }
+        }.start()
+    }
+
+    private class FlashStep(
+        val name: String,
+        val address: Int,
+        val data: ByteArray,
+        val baseProgress: Int,
+        val range: Int,
+        val compress: Boolean
+    )
+
+    private fun doFlash(usbManager: UsbManager, device: UsbDevice, callback: FlashCallback) {
+        Thread.sleep(500)
+
+        val connection = usbManager.openDevice(device)
+            ?: throw IOException("Kan USB-apparaat niet openen")
+
+        try {
+            val intf = UsbUtils.findCdcDataInterface(device)
+                ?: throw IOException("Geen CDC data interface gevonden")
+
+            if (!connection.claimInterface(intf, true)) {
+                throw IOException("Kan USB interface niet claimen")
+            }
+
+            val epOut = UsbUtils.findBulkEndpoint(intf, UsbConstants.USB_DIR_OUT)
+                ?: throw IOException("Geen USB OUT endpoint gevonden")
+            val epIn = UsbUtils.findBulkEndpoint(intf, UsbConstants.USB_DIR_IN)
+                ?: throw IOException("Geen USB IN endpoint gevonden")
+
+            postProgress(callback, 0, "Verbinden met ESP bootloader...")
+
+            val transport = UsbSerialTransport(connection, epOut, epIn)
+
+            val assets = context.assets
+            val bootloader = assets.open("firmware/bootloader.bin").readBytes()
+            val partitions = assets.open("firmware/partitions.bin").readBytes()
+            val bootApp0 = assets.open("firmware/boot_app0.bin").readBytes()
+            val firmware = assets.open("firmware/firmware.bin").readBytes()
+
+            val totalSize = bootloader.size + partitions.size + bootApp0.size + firmware.size
+
+            val steps = listOf(
+                FlashStep("Bootloader", 0x0, bootloader, 30, 10, false),
+                FlashStep("Partitie tabel", 0x8000, partitions, 40, 10, false),
+                FlashStep("Boot app0", 0xe000, bootApp0, 50, 10, false),
+                FlashStep("Firmware", 0x10000, firmware, 60, 35, true)
+            )
+
+            postProgress(callback, 5, "Sync met bootloader...")
+            val api = EspFlasherApi.connect(transport)
+                .withCallBack(object : ProgressCallback {
+                    override fun onProgress(pct: Float) {
+                        Log.d(TAG, "Lib progress: $pct%")
+                    }
+                    override fun onInfo(value: String) {
+                        Log.d(TAG, "Info: $value")
+                    }
+                })
+
+            postProgress(callback, 10, "Chip detecteren...")
+            val detected = api.chipDetect()
+            val chipId = detected.getChipId()
+            Log.i(TAG, "Detected chip: $chipId")
+            postProgress(callback, 15, "Chip: ${chipId.readableName}")
+
+            postProgress(callback, 20, "Stub laden...")
+            val stub = detected.loadStub()
+
+            postProgress(callback, 25, "Flash wissen...")
+            stub.eraseFlash()
+
+            for (step in steps) {
+                val sizeStr = if (step.data.size > 1024) "${step.data.size / 1024}KB" else "${step.data.size} bytes"
+                postProgress(callback, step.baseProgress, "${step.name} schrijven ($sizeStr)...")
+
+                val writeStub = if (step.compress) stub.withCompression(true) else stub.withCompression(false)
+                writeStub.writeFlash(step.address, step.data)
+
+                val endProgress = step.baseProgress + step.range
+                postProgress(callback, endProgress.coerceAtMost(95), "${step.name} geschreven")
+            }
+
+            postProgress(callback, 95, "ESP resetten...")
+            stub.reset()
+
+            postProgress(callback, 100, "Firmware geflashed!")
+            handler.post { callback.onComplete() }
+        } finally {
+            connection.close()
+        }
+    }
+
+    private fun postProgress(callback: FlashCallback, percent: Int, message: String) {
+        Log.d(TAG, "Progress $percent%: $message")
+        handler.post { callback.onProgress(percent, message) }
+    }
+}