Altera RapidIO II MegaCore Function - Manual (Page 100)

4–58 Chapter 4: Functional Description
Logical Layer Interfaces
RapidIO II MegaCore Function August 2014 Altera Corporation
User Guide
The initial ten bytes of the packet contain header information. Table 4–33 lists the
header fields and their values in this example.
User Receiving Write Request
Table 4–34 lists the Avalon-ST pass-through interface usage example this section
describes.
Table 4–33. NWRITE Request Transmit Example: RapidIO Header Fields on the gen_tx_data Bus
Field
gen_tx_data
Bits
Value Comment
ackID [127:122] 6'h00
Value is a don’t care, because it is overwritten by the Physical
layer ackID value before the packet is transmitted on the
RapidIO link.
VC [121] 0 The RapidIO II IP core supports only VC0.
CRF [120] 0
prio[1:0] [119:118] 2'b00
tt[1:0] [117:116] 2'b00 The value of 0 indicates 8-bit device IDs.
ftype[3:0] [115:112] 4'b0101 The value of 5 indicates a Write Class packet.
destinationId[7:0] [111:104] 8'hDD
sourceId[7:0] [103:96] 8'hAA
ttype[3:0] [95:92] 4'b0100 The value of 4 indicates an NWRITE transaction.
size[3:0] [91:88] 4'b1100
The size and wdptr values encode the maximum size of the
payload field. In this example, they decode to a value of 64
bytes. For details, refer to Table 4-4 in Part 1: Input/Output
Logical Specification of the RapidIO Interconnect Specification,
Revision 2.2.
transactionID[7:0] [87:80] 8'h00 Not used for NWRITE transactions.
address[28:0] [79:51]
{28’hFEDCBA9,
1’b0}
wdptr [50] 1 Refer to the comment for size.
xamsbs[1:0] [49:48] 2’b00
Table 4–34. Avalon-ST Pass-Through Interface Usage Example: Receive NWRITE Request
User Operation
Operation
Type
RapidIO Transaction Priority
Device ID
Width
Payload Size
(Bytes)
Receive write request Rx NWRITE 0 8 40