Packet Format

The CRKit packet format is as shown in Figure 1. Host must conform to this specification to enable board level communication.

Figure 1 - Packet Format

The packet consists of following headers :

• Ethernet
• IPv4
• UDP
• TCP

UDP is used for Host <-> CRKit communication e.g. RMAP read/write, status and data transmission.

At this point, fragmentation/reassembly at IP level is not yet supported. We may include this feature in the future. Note that the IP packet size must be 46-1500 bytes e.g. size of ethernet payload. Hence, max. UDP payload is 1500 - 20 (IP header) - 8 (UDP header) = 1472 bytes.

Furthermore, additional header information is added into the payload region for user specific control information :

• RMAP Packet
• Status Packet
• Data Packet

Some sample packet configurations :

• RMAP
• Data

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