Altera HyperTransport MegaCore Function - Manual (Page 44)

3–18 Chapter 3: Specifications
HyperTransport MegaCore Function Specification
HyperTransport MegaCore Function User Guide © November 2009 Altera Corporation
Preliminary
Sop_o Output Start of packet. This signal indicates the start of packet. When Sop_o is high, start of
packet is present on Dat_o[63:0] and is aligned to the least significant byte. Sop_o
is qualified with the Val_o signal. If Val_o is low, Sop_o must be ignored.
Eop_o Output End of packet. This signal indicates the end of packet. When Eop_o is high, end of data
packet is present on Dat_o[63:0] and is aligned to the least significant byte. Eop_o
is qualified with the Val_o signal. If Val_o is low, Eop_o must be ignored.
Val_o Output Data valid. This signal indicates that the data driven on Dat_o[63:0] is valid. Val_o
is updated on every RefClk edge at which Ena_i is sampled asserted, and holds its
current value along with the Dat_o bus when Ena_i is sampled deasserted. When
Val_o is asserted, the Atlantic data interface signals are valid. When Val_o is
deasserted, the Atlantic data interface signals are invalid and must be ignored. To
determine whether new data has been received, the master must qualify the
Val_o
signal with the previous state of the Ena_i signal.
The Rx buffers always provide all words of a packet on consecutive cycles ( Val_o
asserted) as long as Ena_i remains asserted during the packet. In addition, if Ena_i is
asserted on the last word of a packet and the next packet is available, the next packet
starts on the cycle immediately after the current packet completes.
Dav_o Output Data available. This signal functions as the Dav signal in the Atlantic interface
specification with the HyperTransport MegaCore function as the slave source. If Dav_o
is high, the buffer has at least one command/data packet available to be read. If this
signal is not asserted, it indicates that there are no valid packets available to be read.
Ena_i Input Data transfer enable. This signal functions as the Ena signal in the Atlantic interface
specification with the HyperTransport MegaCore function as a slave source. Ena_i is
driven by the interface master and is used to control the flow of data across the interface.
Ena_i behaves as a read enable from master to slave. When the slave observes Ena_i
asserted on the RefClk rising edge, it drives, on the following RefClk rising edge, the
Atlantic data interface signals and asserts Val_o . The master captures the data interface
signals on the following RefClk rising edge.
BarHit_o[2:0] Output BAR match indication. For the Rx posted and Rx non-posted interfaces, this bus indicates
which BAR the packet matched.
000 32-bit BAR0 or 64-bit BAR01
001 32-bit BAR1
010 32-bit BAR2 or 64-bit BAR23
011 32-bit BAR3
100 32-bit BAR4 or 64-bit BAR45
101 32-bit BAR5
110 Not used
111 Non-address packet
This bus is valid only when Val_o and Sop_o are asserted.
Because responses are not claimed due to address matches, this bus does not exist in
the response buffer interface.
Table 3–5. Rx Command/Data Buffer Interface Signals (Part 2 of 2)
Signal Name Direction Description