diff --git a/avr/MESSAGES b/avr/MESSAGES
index 60cdbdf..5ab2ead 100644
--- a/avr/MESSAGES
+++ b/avr/MESSAGES
@@ -16,6 +16,8 @@ Offset Length Meaning
      3      1 source address
 ---------------------------------------------------------
      4      n payload data (depending on command code)
+---------------------------------------------------------
+     4+n    1 CRC8 byte
 
 
 
@@ -221,3 +223,88 @@ Offset Length Meaning
 
 
 
+
+
+
+FLASHSTART Message
+==================
+
+Offset Length Meaning
+---------------------------------------------------------
+     0      1 destination address
+     1      1 remaining message length
+     2      1 command code
+     3      1 source address
+---------------------------------------------------------
+     4      4 UID
+     8      2 firmware type
+    10      2 firmware version
+
+
+
+FLASHREADY Message
+==================
+
+Offset Length Meaning
+---------------------------------------------------------
+     0      1 destination address
+     1      1 remaining message length
+     2      1 command code
+     3      1 source address
+---------------------------------------------------------
+     4      4 UID
+     8      2 firmware type
+    10      2 firmware version
+    12      2 page size in bytes
+
+
+
+FLASHDATA Message
+=================
+
+Offset Length Meaning
+---------------------------------------------------------
+     0      1 destination address
+     1      1 remaining message length
+     2      1 command code
+     3      1 source address
+---------------------------------------------------------
+     4      2 address
+     6      n data bytes (max 124 bytes)
+
+
+
+FLASHEND Message
+================
+
+Offset Length Meaning
+---------------------------------------------------------
+     0      1 destination address
+     1      1 remaining message length
+     2      1 command code
+     3      1 source address
+---------------------------------------------------------
+     4      1 code (0 if okay, error code to abort)
+
+
+
+FLASHRESPONSE Message
+=====================
+
+Offset Length Meaning
+---------------------------------------------------------
+     0      1 destination address
+     1      1 remaining message length
+     2      1 command code
+     3      1 source address
+---------------------------------------------------------
+     4      1 response code
+
+
+
+
+
+
+
+
+