Altera RapidIO II MegaCore Function - Manual (Page 105)

Chapter 4: Functional Description 4–63
Logical Layer Interfaces
August 2014 Altera Corporation RapidIO II MegaCore Function
User Guide
Table 4–38 lists the header fields of the received response packet in this example.
User Receiving Read Request and Sending Read Response
Table 4–39 lists the Avalon-ST pass-through interface usage example this section
describes. Refer to “Transaction ID Ranges” on page 4–48 and “Receiver” on
page 4–71 for a description of the RapidIO II IP core variations in which this example
transaction is processed through the Avalon-ST pass-through interface rather than
being processed through one of the I/O Logical layer modules.
Table 4–38. NREAD Response Receive Example: RapidIO Header Fields in gen_rx_hd_data Bus
Field
gen_rx_hd_data
Bits
Value Comment
pd_size[8:0] [114:106] 9’h020 Payload data size is 0x20 (decimal 32).
VC [105] 0 The RapidIO II IP core supports only VC0.
CRF [104] 0
prio[1:0] [103:102] 2’b10
Priority of the response packet. Value must be higher
than the priority value of the request packet. In this
example, the response packet has a priority value of
2’b10 and the original request has a priority value of
2’b01.
tt[1:0] [101:100] 2’b01 Indicates 16-bit device IDs.
ftype[3:0] [99:96] 4’b1101
The value of 4’hD (decimal 13) indicates a Response
Class packet.
destinationID[15:0] [95:80] 16’hAAAA The sourceID and destinationID of the NREAD request
are swapped in the response transaction.
sourceID[15:0] [79:64] 16’hDDDD
ttype[3:0] [63:60] 4’b1000
The value of 8 indicates a Response transaction with
data payload.
status[3:0] [59:56] 4’b0000
The value of 0 indicates Done. The current packet
successfully completes the requested transaction.
transactionID[7:0] [55:48] 8'hBB
Value in the response packet matches the
transactionID
of the corresponding request packet.
Reserved[47:0] [47:0] 48’h0
Table 4–39. Avalon-ST Pass-Through Interface Usage Example: Receiving NREAD Request and Sending Response
User Operation
Operation
Type
RapidIO Transaction Priority
Device ID
Width
Payload Size
(Bytes)
Receive read request Rx NREAD 1 16 32
Send read response Tx Response with payload 2 16 32