diff --git a/devel/devel20210930-B16-changelog.txt b/devel/devel20210930-B16-changelog.txt
new file mode 100644
index 0000000..6ae972d
--- /dev/null
+++ b/devel/devel20210930-B16-changelog.txt
@@ -0,0 +1 @@
+DFM: check for bit errors
diff --git a/devel/devel20210930-B16-full.bin b/devel/devel20210930-B16-full.bin
new file mode 100644
index 0000000..afb1c79
Binary files /dev/null and b/devel/devel20210930-B16-full.bin differ
diff --git a/devel/update-info.html b/devel/update-info.html
index 81e20bd..53bd32a 100644
--- a/devel/update-info.html
+++ b/devel/update-info.html
@@ -1 +1 @@
-<html><body><p>devel20210928-B16</p></body></html>
+<html><body><p>devel20210930-B16</p></body></html>
diff --git a/devel/update.ino.bin b/devel/update.ino.bin
index b4f2786..62944d1 100644
Binary files a/devel/update.ino.bin and b/devel/update.ino.bin differ
diff --git a/download.html b/download.html
index 4d6fba1..f891436 100644
--- a/download.html
+++ b/download.html
@@ -24,12 +24,16 @@
 <li><a href="master/master_v0.6a-full.bin">master_v0.6a-full.bin</a> (Apr 29 21:03:35 2019)</li>
 
 </ul><h2>Development repository</h2><ul>
-<li><a href="devel/update.ino.bin">update.ino.bin</a> (Sep 28 15:31:36 2021)
+<li><a href="devel/update.ino.bin">update.ino.bin</a> (Sep 30 12:57:40 2021)
 </li>
 
 <li><a href="devel/update.fs.bin">update.fs.bin</a> (Sep 28 15:31:36 2021)
 </li>
 
+<li><a href="devel/devel20210930-B16-full.bin">devel20210930-B16-full.bin</a> (Sep 30 12:57:40 2021)
+<br>DFM: check for bit errors
+</li>
+
 <li><a href="devel/devel20210928-B16-full.bin">devel20210928-B16-full.bin</a> (Sep 28 15:31:36 2021)
 <br>less confusing M10/M20
 </li>
