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src/robomaster.h

@@ -12,7 +12,11 @@ uint16_t crc16(const void *block, size_t length);
 #define PACKED __attribute__((__packed__))
 
 struct PACKED Header {
+
+  // The preamble marks the start of a message and is always 0x55
   uint8_t preamble;
+
+  // The length of the message includes the preamble and CRC16 at the end
   union {
       uint16_t length;
       struct {
@@ -20,9 +24,20 @@ struct PACKED Header {
 	  uint8_t length_h;
       };
   };
+
+  // This is a CRC8 checksum for the preamble and length together
   uint8_t crc;
+
+  // hostbyte of the message sender
   uint8_t sender;
+
+  // hostbyte of the message receiver
   uint8_t receiver;
+
+  // Each message has a sequence ID
+  // The Robomaster will respond with the same ID for each request
+  // The value of the sequence ID doesn't matter to the Robomaster
+  // Repeating sequence IDs are acceptable
   union {
       int16_t seq_id;
       struct {
@@ -30,6 +45,9 @@ struct PACKED Header {
 	  uint8_t seq_id_h;
       };
   };
+
+  // The message attribute flags designate if a response is needed or if the
+  // message is a response.
   union {
     uint8_t attribute;
     struct {
@@ -38,8 +56,11 @@ struct PACKED Header {
       bool is_ack : 1;
     };
   };
+
+  // Each command has a cmdset and cmdid that together make a cmd key
   uint8_t cmdset;
   uint8_t cmdid;
+
 };
 
 struct PACKED Message {