A value of one in the first byte of a message indicates the beginning of a multiple byte extended message. The minimum number of bytes sent for an extended message is three. The extended message format and the extended message code are shown in Table 3.84 and 3.85 respectively.
Table 3.84 Extended Message Format |
|
|
|
|
|
|
|
|
|
|
|
| INTERFACE | ||||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| Bit |
| 7 |
|
|
| 6 | 5 | 4 | 3 |
| 2 | 1 | 0 |
|
|
|
|
| ||||||||
Byte |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| ||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0 |
|
|
|
|
|
|
|
|
|
|
| Extended message (01h) |
|
|
|
|
|
|
|
|
|
|
| ||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
1 |
|
|
|
|
|
|
|
|
|
|
| Extended message length (n) |
|
|
|
|
|
|
|
|
|
| |||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
2 |
|
|
|
|
|
|
|
|
|
|
| Extended message code (y) |
|
|
|
|
|
|
|
|
|
| |||||||
3 |
|
|
|
|
|
|
|
|
|
|
| Extended message arguments |
|
|
|
|
|
|
|
|
|
| |||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| n+1 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The extended message length specifies the length in bytes of the extended message code plus the extended message arguments to follow. Therefore, the total length of the message is equal to the extended message length plus two. A value of zero for extended message length indicates 256 bytes follow.
The extended message codes are listed in Table 3.85 The extended message arguments are specified within the extended message descriptions.
Table 3.85 Extended Message Codes
Code(s) | Description |
|
|
02h | Reserved (See Note) |
|
|
00h | MODIFY DATA POINTER |
|
|
01h | SYNCHRONOUS DATA TRANSFER REQUEST |
|
|
03h | WIDE DATA TRANSFER REQUEST |
|
|
04h - 7Fh | Reserved |
|
|
80h - FFh | Vendor Specific |
|
|
Note: Extended message code 02h was used for the EXTENDED IDENTIFY message in
M3099GX/GH OEM Manual |