diff --git a/firmware/Please read me before update !!!.txt b/firmware/Please read me before update !!!.txt
new file mode 100644
index 0000000..0aeba10
--- /dev/null
+++ b/firmware/Please read me before update !!!.txt	
@@ -0,0 +1,6 @@
+For version earlier than V3.0.33 can only be updated to V3.0.33, if you update it to V3.1.X, there will be 404 error if you visit the web console.
+Still you can update it back, via http://ip_of_your_clock/update.
+
+V3.0.X has different software structure with the V3.1.X, they should not be updated to each other.
+
+Thank you.
\ No newline at end of file
diff --git a/firmware/V3.1.0/firmware.bin b/firmware/V3.1.0/firmware.bin
deleted file mode 100644
index b97bf7e..0000000
Binary files a/firmware/V3.1.0/firmware.bin and /dev/null differ
diff --git a/firmware/V3.1.0/update history.txt b/firmware/V3.1.0/update history.txt
deleted file mode 100644
index ea30f8a..0000000
--- a/firmware/V3.1.0/update history.txt	
+++ /dev/null
@@ -1,4 +0,0 @@
-V3.1.0 20230827
-The new and stable version, with 13 languages on the web.
-
-Due to software structure reason, old firmware earlier than this version is not supported update to this version.
\ No newline at end of file
diff --git a/firmware/V3.1.1/firmware.bin b/firmware/V3.1.1/firmware.bin
deleted file mode 100644
index 730eb74..0000000
Binary files a/firmware/V3.1.1/firmware.bin and /dev/null differ
diff --git a/firmware/V3.1.1/update history.txt b/firmware/V3.1.1/update history.txt
deleted file mode 100644
index e23f7d9..0000000
--- a/firmware/V3.1.1/update history.txt	
+++ /dev/null
@@ -1,7 +0,0 @@
-V3.1.1 20230827
-1) Small fix, when play the "fack" gif file, which contains no gif content, will cause system reboot.
-
-V3.1.0 20230827
-The new and stable version, with 13 languages on the web.
-
-Due to software structure reason, old firmware earlier than this version is not supported update to this version.
\ No newline at end of file
diff --git a/firmware/V3.1.2/firmware-V3.1.2.bin b/firmware/V3.1.2/firmware-V3.1.2.bin
deleted file mode 100644
index ba2e2f0..0000000
Binary files a/firmware/V3.1.2/firmware-V3.1.2.bin and /dev/null differ
diff --git a/firmware/V3.1.3/firmware-V3.1.3-smalltv.bin b/firmware/V3.1.3/firmware-V3.1.3-smalltv.bin
deleted file mode 100644
index 8d8651c..0000000
Binary files a/firmware/V3.1.3/firmware-V3.1.3-smalltv.bin and /dev/null differ
diff --git a/firmware/V3.1.3/update history.txt b/firmware/V3.1.3/update history.txt
deleted file mode 100644
index 2df0f2a..0000000
--- a/firmware/V3.1.3/update history.txt	
+++ /dev/null
@@ -1,10 +0,0 @@
-V3.1.3 20231206
-1) Fix connect to open WiFi.
-
-V3.1.1 20230827
-1) Small fix, when play the "fack" gif file, which contains no gif content, will cause system reboot.
-
-V3.1.0 20230827
-The new and stable version, with 13 languages on the web.
-
-Due to software structure reason, old firmware earlier than this version is not supported update to this version.
\ No newline at end of file