Filter
Top Products
244 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
Media and Switch Fabric Interface
Control words are inserted only between burst transfers; once a transfer has begun, data words are
sent uninterrupted until either End of Packet or a multiple of 16 bytes is reached. The order of bytes
within the SPI-4 data burst is shown in Table 84.
The most significant bits of the bytes correspond to bits 15 and 7. On data transfers that do not end
on an even byte-boundary, the unused byte on bits [7:0] is set to all zeros.
Table 83. SPI-4 Control Word Format
Bit
Position
Label Description
15 Type
Control Word Type.
• 1—payload control word (payload transfer will immediately follow the control word).
• 0—idle or training control word.
14:13 EOPS
End-of-Packet (EOP) Status.
Set to the following values below according to the status of the immediately preceding
payload transfer.
• 00—Not an EOP.
• 01—EOP Abort (application-specific error condition).
• 10—EOP Normal termination, 2 bytes valid.
• 11—EOP Normal termination, 1 byte valid.
EOPS is valid in the first Control Word following a burst transfer. It is ignored and set to 00
otherwise.
12 SOP
Start-of-Packet (SOP).
• Set to 1 if the payload transfer immediately following the Control Word corresponds to
the start of a packet; set to 0 otherwise.
• Set to 0 in all idle and training control words.
11:4 ADR
Port Address.
8-bit port address of the payload data transfer immediately following the Control Word.
None of the addresses are reserved (all are available for payload transfer).
• Set to all zeros in all idle Control Words.
• Set to all ones in all training Control Words.
3:0 DIP-4
4-bit Diagonal Interleaved Parity.
4-bit odd parity computed over the current Control Word and the immediately preceding
data words (if any) following the last Control Word.