Mii data

The Mii Channel and some games such as Wii Sports store Mii data in the Wiimote internal memory.

Data from Miis in the Mii Parade is stored in the Wiimote, even though those Miis are not shown in the Wiimote Mii view. If all the slots are filled up and there is no space for more Miis, presumably this doesn't happen.

Overall format

The Mii data is stored on the Wiimote in two blocks. Each block is composed of 750 bytes of Mii data, followed by a 2 byte CRC. If the data in the first block does not match the CRC for that block, the second block is used instead. At that point, if the CRC of the second block does not match its data, no Mii data will be available.

The blocks are 752 bytes in length (0x2f0 bytes), and are stored consecutively starting at address 0x0fca in the Wiimote memory.

Example dumps

[1] - Mii data. First Mii is a generic default Mii with the name "test1". The following three Miis are not visible in the Mii Channel and are from the Mii Parade.

Block format

At the beginning of each block, there is a 4-byte value ('RNCD') which may be a Mii software version number, as it is the same across multiple Wiis and multiple Wiimotes. After these 4 bytes, there are 2 bytes which determine which slots are Mii parade slots. Left shift 0x0001 by the slot number to set it as Mii parade (hidden when viewed on the Wiimote). If a slot is empty, or filled by a non-parade Mii, its parade slot bit will be set to 0.

The last two bytes of the block are a CRC-16 CCITT of the previous 750 bytes (polynomial 0x1021, starting value 0x0000). C code to update CRC

This is a short (but working) version of the CRC calculation algorithm, written in Java (should be easy to adapt for other programming languages):

 /**
  * Calculate a modified CRC16-CCITT checksum of a byte array, as used for
  * checking the validity of a Mii data block stored on a Wiimote.
  *
  * @param bytes the byte array to calculate the checksum for
  * @return the checksum (in the lower 16 bits)
  */
 static int crc (byte[] bytes) {
     int crc = 0x0000;
     for (int byteIndex = 0; byteIndex < bytes.length; byteIndex++) {
         for (int bitIndex = 7; bitIndex >= 0; bitIndex--) {
             crc = (((crc << 1) | ((bytes[byteIndex] >> bitIndex) & 0x1)) ^
             (((crc & 0x8000) != 0) ? 0x1021 : 0)); 
         }
     }
     for (int counter = 16; counter > 0; counter--) {
         crc = ((crc << 1) ^ (((crc & 0x8000) != 0) ? 0x1021 : 0));
     }
     return (crc & 0xFFFF);
 }

Unknown Data:

• Effect of changing the first 4 bytes of the Mii block.
• What the 7 leading bits in the Mii parade bytes are used for.

Mii format

Strings are apparently stored in Unicode format (UTF-16), big-endian. Miis with Japanese Unicode characters in their names work (and are displayed correctly) on US Wii hardware.

Data Validation in the Mii Channel:

Setting invalid facial features, or colors over the limit (with the exception of Favorite color) in any fields appears to invalidate that Mii, and it does not show up when the Wiimote slots are viewed on the Wii (though all other Miis on the Wiimote do show up).

Weight and height seem to be clamped to 0x7F. Setting these bytes of 0xFF does not result in a super tall or fat Mii, but one exactly the same as if 0x7F were set. When the Mii is edited on the Wii then saved back to the controller, these bytes are back to 0x7F.

Hair type, eyebrow type, eye type, lip type and nose type use a pre-determined set of valid entries which are not sequential with the order in which they are displayed. They do, however, use the expected range of values from 0 to n - 1.

The Mii ID is a unique identifier for the Mii but also determines whether the mii is 'special' (with gold pants) or not. More on special Miis.

Eyebrow rotation and eye rotation both have differing default values based upon the type selected.

Each Mii is 0x4a bytes:

Mii data structure (work in progress):

typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;

#define MII_NAME_LENGTH			10
#define MII_CREATOR_NAME_LENGTH		10

typedef struct
{
// addr: 0x00 & 0x01
	u16 invalid:1; // doesn't seem to have any effect?
	u16 isGirl:1;
	u16 month:4;
	u16 day:5;
	u16 favColor:4;		 // 0 - 11 (changing to 1111, along with setting the preceeding bit 
              		           // results in a grey shirt, some values over 11 will crash the Wii 
		 // when trying to change the favorite color).
	u16 isFavorite:1;

// addr: 0x02 through 0x15
	u16 name[MII_NAME_LENGTH];

// addr: 0x16
	u8 height; // 0 - 127

// addr: 0x17
	u8 weight; // 0 - 127

// addr: 0x18 - 0x1B
 	u8 miiID1; 	           // Unique Mii identifier. Seems to increment with time. Also can
 	u8 miiID2; 	           // be used to change colour of Mii Trousers (see 'See Also' links)
 	u8 miiID3;
 	u8 miiID4;

// addr: 0x1C through 0x1F
	u8 systemID0;	 // Checksum8 of first 3 bytes of mac addr
	u8 systemID1;	 // mac addr 3rd-to-last byte
	u8 systemID2;	 // mac addr 2nd-to-last byte
	u8 systemID3;	 // mac addr last byte

// addr: 0x20 & 0x21
	u16 faceShape:3; // 0 - 7
	u16 skinColor:3; // 0 - 5
	u16 facialFeature:4; // 0 - 11
	u16 unknown:3; // Mii appears unaffected by changes to this data 
	u16 mingleOff:1; // 0 = Mingle, 1 = Don't Mingle
	u16 unknown:1; // Mii appears unaffected by changes to this data
	u16 downloaded:1; // If the Mii has been downloaded from the Check Mii Out Channel

// addr: 0x22 & 0x23
	u16 hairType:7; // 0 - 71, Value is non-sequential with regard to page, row and column
	u16 hairColor:3; // 0 - 7
	u16 hairPart:1; // 0 = Normal, 1 = Reversed
	u16 unknown:5;

// addr: 0x24 through 0x27
	u32 eyebrowType:5; // 0 - 23, Value is non-sequential with regard to page, row and column
	u32 unknown:1;
	u32 eyebrowRotation:4; // 0 - 11, Default value varies based on eyebrow type
	u32 unknown:6;
	u32 eyebrowColor:3; // 0 - 7
	u32 eyebrowSize:4;	 // 0 - 8, Default = 4
	u32 eyebrowVertPos:5; // 3 - 18, Default = 10
	u32 eyebrowHorizSpacing:4; // 0 - 12, Default = 2

// addr: 0x28 through 0x2B
	u32 eyeType:6; // 0 - 47, Value is non-sequential with regard to page, row and column
	u32 unknown:2;
	u32 eyeRotation:3; // 0 - 7, Default value varies based on eye type
	u32 eyeVertPos:5; // 0 - 18, Default = 12, Smaller Numbers = Higher Up
	u32 eyeColor:3; // 0 - 5
	u32 unknown:1;
	u32 eyeSize:3; // 0 - 7, Default = 4
	u32 eyeHorizSpacing:4; // 0 - 12, Default = 2
	u32 unknown:5;

// addr: 0x2C & 0x2D
	u16 noseType:4; // 0 - 11, Value is non-sequential with regard to row and column
	u16 noseSize:4; // 0 - 8, Default = 4
	u16 noseVertPos:5; // 0 - 18, Default = 9
	u16 unknown:3;

// addr: 0x2E & 2F
	u16 lipType:5; // 0 - 23, Value is non-sequential with regard to page, row and column
	u16 lipColor:2; // 0 - 2
	u16 lipSize:4; // 0 - 8, Default = 4
	u16 lipVertPos:5; // 0 - 18, Default = 13

// addr: 0x30 & 0x31
	u16 glassesType:4; // 0 - 8
	u16 glassesColor:3; // 0 - 5
	u16 unknown:1; // when turned on mii does not appear (use not known)
	u16 glassesSize:3; // 0 - 7, Default = 4
	u16 glassesVertPos:5; // 0 - 20, Default = 10

// addr: 0x32 & 33
	u16 mustacheType:2; // 0 - 3
	u16 beardType:2; // 0 - 3
	u16 facialHairColor:3; // 0 - 7
	u16 mustacheSize:4; // 0 - 8, Default = 4
	u16 mustacheVertPos:5; // 0 - 16, Default = 10

// addr: 0x34 & 0x35
	u16 moleOn:1; // 0 = No Mole, 1 = Has Mole
	u16 moleSize:4; // 0 - 8, Default = 4
	u16 moleVertPos:5; // 0 - 30, Default = 20
	u16 moleHorizPos:5; // 0 - 16, Default = 2
	u16 unknown:1; 

// addr: 0x36 through 0x49
	u16 creatorName[MII_CREATOR_NAME_LENGTH];
} MII_DATA_STRUCT;