Altera Interlaken MegaCore Function - Manual (Page 56)

5–4 Chapter 5: Signals
Interlaken MegaCore Function Reset Signals
Interlaken MegaCore Function June 2012 Altera Corporation
User Guide
Interlaken MegaCore Function Reset Signals
If you turn off Exclude transceivers, your Interlaken MegaCore function includes a
reset controller block that implements the full MegaCore function reset sequence after
the application asserts a single global reset signal.
Table 5–4 lists the Interlaken
MegaCore function global reset signal.
If you turn on Exclude transceivers, your Interlaken MegaCore function does not
include a reset controller. In that case, you must control multiple reset signals for
individual blocks to enforce the correct reset sequence for the Interlaken MegaCore
function.
Table B–2 on page B–7 lists the individual reset signals visible when you
turn on Exclude transceivers, and “Required Reset Sequence” on page B–8 describes
the required reset sequence.
rx_status_overflow Output
Indicates that the RX MAC and channel filter blocks are unable to
process data as fast as it arrives on the Interlaken link, and data is lost
or corrupted. You can use the out-of-band flow control block to
backpressure the Interlaken link partner.
Note to Table 5–2 :
(1) All of the RX status signals are clocked by rx_mac_c_clk.
Table 5–2. Interlaken RX Status Interface Signals (1) (Part 2 of 2)
Signal Direction Description
Table 5–3. Interlaken TX Status Interface Signals (1)
Signal Direction Description
tx_status_hungry Output
Indicates that the TX FIFO in the MAC TX block is close to underflow. By default,
the Interlaken MegaCore function has TX underflow protection enabled, and the
TX FIFO cannot actually underflow: in response to a near-underflow condition,
the PCS TX block inserts IDLE words in the outgoing data stream (on
tx_serial_dataN_export
or tx_dataN_export). The application can
monitor or ignore this signal. The signal warns the monitoring application that
data density on the incoming channels is not ideal.
tx_status_overflow Output
Indicates that the TX FIFO in the MAX TX block has overflowed. Data has been
lost or corrupted.
tx_status_underflow Output
Indicates that the TX FIFO in the MAC TX block has underflowed. By default, this
condition cannot occur. The Interlaken MegaCore function has TX underflow
protection enabled, and the TX FIFO cannot actually underflow: in response to a
near-underflow condition, indicated by tx_status_hungry, the PCS TX block
inserts IDLE words in the outgoing data stream (on tx_serial_dataN_export
or tx_dataN_export).
Note to Table 5–3 :
(1) All of the TX status signals are clocked by tx_mac_c_clk.
Table 5–4. Global Reset Signal
Signal Direction Description
reset_export Input
Asynchronous reset for the full Interlaken MegaCore function, including the RX and TX MAC
blocks, the full TX FIFO, the RX and TX PCS blocks, and the transceivers. This reset signal
can be asserted and deasserted asynchronously, but must remain asserted at least four
cal_blk_clk
clock cycles.