diff --git a/app/src/main/cpp/MicroPhoto.cpp b/app/src/main/cpp/MicroPhoto.cpp
index e624286c..1f2bb614 100644
--- a/app/src/main/cpp/MicroPhoto.cpp
+++ b/app/src/main/cpp/MicroPhoto.cpp
@@ -527,6 +527,22 @@ Java_com_xypower_mpapp_MicroPhotoService_sendHeartbeat(
 
     pTerminal->SendHeartbeat();
 
+#ifdef OUTPUT_DBG_INFO
+    std::thread t([]()
+    {
+        time_t ts = time(NULL);
+        int ldr = GpioControl::getLightAdc();
+        
+        char buf[64] = { 0 };
+        snprintf(buf, sizeof(buf), "%s %d\r\n", FormatLocalDateTime(ts).c_str(), ldr);
+
+        appendFile("/sdcard/com.xypower.mpapp/tmp/ldr.txt", buf, strlen(buf));
+
+
+    });
+    t.detach();
+#endif
+
     return JNI_TRUE;
 }