1.1.3.2 Data Gen

Based on the requests from the Data Store module, the Data Gen module generates Ethernet packets with the appropriate control and status data to be transmitted to IAP Target.

The Ethernet packet consists of the following fields:
  • Destination Address (DA): Custom destination address used for the demo design.
  • Source Address (SA): MAC address associated with the port through which the Ethernet packet is transmitted.
  • Ethernet Type: Reserved Ethernet type used for the demo design.
  • Command: Each activity has a specific command value for a better readability.
  • Length: Payload length value of control and data packets.
  • Offset: TBD
  • Payload: Control packet can have a maximum payload length of 64 bytes and the data packet can have a maximum payload length of 1024 byes.
  • FCS: Four-byte frame check sequence as defined in clause 4 of [IEEE 802.3].
  • EOF: End of packet.
The Data Gen module uses this custom packet structure and fields while generating control and data Ethernet packets in this demo design. The Control Ethernet packet of length 92 bytes carries the necessary information to IAP Target for the following activities.
  • Data Transfer request: This activity happens frequently to check the status of IAP Target for starting the data transfer. IAP Initiator keeps sending this request packet until the response packet is received.
  • Last Burst and Last Burst size: This packet indicates the end of the SPI image to the IAP Target.

The data packet of length 1052 bytes carries the SPI image to the target, which is stored in the External SPI Flash of IAP Target. Control packet is also used to send image authentication and program requests. For any given data transfer, a total of 2 KB data (2 data packets) are transmitted every time.

The following table lists the byte format of a control and data packet.

Table 1-1. Ethernet Packet Structure (Control and Data)
Byte NumberSizeFieldValue
1-88 bytes

Destination Address

Source Address

48'hFFFF_FFFF_FFFF

16'hD0AB

9-168 bytesSource Address32'hD5576610
Ethernet Type16’h0700
Command

16’h0004 – Control

16’h0005 – Payload

16’h0007 – IAP Authenticate

16’h0008 – IAP Program

16’h0009 – Send version Number

16’h000A – Clear all interrupts

16-238 bytesZero’s32’h00000000
Length0x0040 – 64 bytes
0x0400 – 1024 bytes
Offset16’h0000
24-8736 bytesPayload (Control Information)

64’h0000000000000000 – For Control Info packet

{Burst size, Last burst info} – For Authenticate, Program packets

Data Packet
24-10471024 bytesPayload (IAP Data)1024 Bytes of IAP Data
Last 44 bytesFCSCore10GMAC computes the FCS and appends to the Frame before transmitting out.