Altera RapidIO MegaCore Function - Manual (Page 128)

5–14 Chapter 5: Signals
Transport and Logical Layer Signals
RapidIO MegaCore Function August 2014 Altera Corporation
User Guide
Table 5–19 describes the Avalon-ST pass-through interface transmission (Tx) signals.
Table 5–19. Avalon-ST Pass-Through Interface Transmission Signals
Signal Type Function
gen_tx_ready Output
Indicates that the IP core is ready to receive data on the next clock cycle.
Asserted by the Avalon-ST sink to mark ready cycles, which are the cycles in
which transfers can take place. If ready is asserted on cycle N, the cycle
(N+READY_LATENCY) is a ready cycle.
In the RapidIO IP core, READY_LATENCY is equal to 1, so the cycle immediately
following the rising clock edge on which gen_tx_ready is detected as asserted
is the ready cycle.
This signal may alternate between 0 and 1 when the Avalon-ST pass-through
transmitter interface is idle. After gen_tx_valid is asserted, gen_tx_ready
remains asserted for the duration of the packet transmission, unless the
Physical layer transmit buffer fills.
gen_tx_valid Input
Used to qualify all the other transmit side of the Avalon-ST pass-through
interface input signals. On every ready cycle in which gen_tx_valid is high,
data is sampled by the IP core.
(1)
gen_tx_startofpacket Input Marks the active cycle containing the start of the packet. (1)
gen_tx_endofpacket Input Marks the active cycle containing the end of the packet. (1)
gen_tx_data Input
A 32-bit wide data bus for 1x variations, or a 64-bit wide data bus for 2x or 4x
variations. Carries the bulk of the information transferred from the source to the
sink.
(1)
gen_tx_empty Input
This bus identifies the number of empty bytes on the last data transfer of the
gen_tx_endofpacket
. For a 32-bit wide data bus, this bus is 2 bits wide. For a
64-bit wide data bus, this bus is 3 bits wide. The least significant bit is ignored
and assumed to be 0. The following values are supported:
(1)
32-bit bus:
2'b0X none
2'b1X [15:0]
64-bit bus:
3'b00X none
3'b01X [15:0]
3'b10X [31:0]
3'b11X [47:0]
gen_tx_error Input
If asserted any time during the packet transfer, this signal indicates the
corresponding data has an error and causes the packet to be dropped by the IP
core. A value of zero on any beat indicates the data on that beat is error-free.
(1)
Note to Table 5–19 :
(1) gen_tx_valid is used to qualify all the other input signals of the transmit side of the Avalon-ST pass-through interface.