DLPU110B April 2021 – August 2022 DLPC6540
The command packet defines the packet format to follow when commands are sent to the DLP Controller. Fields that are always present are indicated in bold, and optional fields are indicated in normal font.
The definition of which fields are present is based on the 1-byte header field. The length field is mandatory if a command is defined as having variable data size.
| Field | Size (bytes) | Description |
|---|---|---|
| Header | 1 | See Table 16-2 below. |
| Opcode | 1 or 2 based on opcode length field in the header | Command opcode. Command opcode number greater than 0xFF should be sent using 2 bytes. Other opcodes can be sent with 1 byte or 2 bytes. In case of 2-byte opcode, first byte is the LSB. |
| Length | 2 or 0 based on data length present field in the header | Length of the command data in bytes following this byte. Checksum is not included in length. For example length=10 means there are 10 bytes of data) after this length field. LSB of length shall be sent first followed by MSB. |
| Data | 0-511 ( total of maximum 512 bytes in the whole message including header and checksum) | Parameters/data |
| Checksum | 1 or 0 (optional as checksum present field of header byte) | Checksum of all bytes in the message
including header bytes. Fletcher's checksum is implemented as
below:-
|
| Bits | Field name | Values |
|---|---|---|
| 0:2 | Destination | See Section 16.3 |
| 3 | Opcode Length | 1 = Two byte opcode 0 = One byte opcode |
| 4 | Datalength Present | 1 = Length field present in the extended header 0 = No length field |
| 5 | Checksum Present | 1 = Checksum present after data bytes 0 = Checksum not present |
| 6 | Reply Requested | 1 = Device will send a response packet to every write command. This field is applicable only for write commands 0 = Response packet not sent for write commands |
| 7 | Read Command | 1 = Read Command 0 = Write Command |