Datasheet

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The first byte is the Message Type (0x10), which identifies this as a command message.

The second and third bytes are 0x1234 (34 12 in little-endian notation), which is the unique command ID. This

value will be compared against the command lookup table and redirected to an appropriate command handler

function if a matching entry was found.

The fourth byte indicates that we have a message payload of 1 byte

The fifth byte is the 1 byte payload: 0xFF

Response Messages

Response messages (Message Type = 0x20) are generated in response to an incoming command, and have the

following structure:

By including the Command ID that this response message is related to, the recipient can more easily correlate

responses and commands. This is useful in situations where multiple commands are sent, and some commands may

take a longer period of time to execute than subsequent commands with a different command ID.

Response messages can only be generate in response to a command message, so the Command ID field should

always be present.

A long response (>16 bytes payload) must be divided into multiple packets. Similar to long commands, the More data

field (bit 7 of byte 3) is used to indicate whether additional packets are available for the same response. On responses

that span more than one packet, the More data bit on the final packet will be set to 0 to indicate that this is the last

packet in the sequence. The SDEP receiver must re-assemble all sub-packets in into one payload when necessary.

If more precise command/response correlation is required a custom protocol should be developed, where a unique

message identifier is included in the payload of each command/response, but this is beyond the scope of this high-

level protocol definition.

A sample response message would be:

0: Message Type (U8)

1+2: Command ID (U16)

3: Payload Len (U8)

4: Payload (...)

0x10

0x34 0x12

0x01

0xFF

Name

Message Type

Command ID

Payload Length

Payload

Type

U16

Meaning

Always '0x20'

Command ID this message is a response to

[7] More data

[6-5] Reserved

[4-0] Payload length (0..16)

Optional response payload (parameters, etc.)