6-11
Simple Serial Interface
CMD_ACK
Description: Positive acknowledgment of received packet
Packet Format
Field Descriptions
This message is sent to the SSI packet transmitter when the received packet passes the
checksum check and no negative acknowledgment conditions apply (see CMD_NAK). If the
data is in response to a command (e.g., PARAM_REQUEST, REQUEST_REVISION, etc.),
no ACK is sent.
Note:
ACK/NAK handshaking can be disabled. We recommend, however, it
be left enabled.
It is not necessary to respond to a valid ACK or NAK message.
Length
Opcode
Message Source
Status
Data
Checksum
0x04
0xD0
Field Name
Format
Size
Description
Length
Length of message (not
including checksum).
1 Byte
Length Field
Opcode
0xD0
1 Byte
Identifies this Opcode type.
Message
Source
0 = Decoder
4 = Host
1 Byte
Identifies where the message is
coming from.
Status
Bit 0: Retransmit
Bit 1-7: unused
1 Byte
Identifies the transmission status.
All unused bits must be set to 0.
Data
None
Checksum
2's complement sum of
message contents
excluding checksum.
2 Bytes
Checksum of message.
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