Achronix Speedster22i 10G/40G/100G Ethernet User Manual
Page 62
62
UG029, September 6, 2013
384-bit).
9
24
RX_FIFO_ALMOST_F_E
RO
15:0: RX FIFO almost empty threshold
31:16: RX FIFO almost full threshold
Read Only Fixed thresholds set with a Core
configuration parameter.
10
28
TX_FIFO_ALMOST_F_E
RO
15:0: TX FIFO almost empty threshold
31:16: TX FIFO almost full threshold
Read Only Fixed thresholds set with a Core
configuration parameter.
11
2C
HASHTABLE_LOAD
WO
Hash table programming. Write only register.
Bits 5:0 specify the hash table address
(code).
Bit 8 enables (1) or disables (0) multicast
frame reception for the entry.
12-15
30-3C
reserved
--
unused
16
40
STATUS
RW
General Purpose Status. Use to monitor the
MAC and PHY interface.
See “0” on page 70.
17
44
TX_IPG_LENGTH
RW
Transmit Inter-Packet-Gap (IPG) value.
A 6-bit value: Depending on LAN or WAN
mode of operation (see
COMMAND_CONFIG, “0” on page 67), the
value has the following meaning:
LAN Mode: Number of octets in steps of 4.
Valid values are 8, 12, 16, ..., 100.
DIC is fully supported for any setting. A
default of 12 (reset value) must be set to
conform to IEEE802.3ae.
Warning: When set to 8, PCS layers may not
be able to perform clock rate compensation.
WAN Mode: Stretch factor.
Valid values are 4..15. The stretch factor is
calculated as (value+1)*8. A default of 12
(reset value) must be set to conform to IEEE
802.3ae (i.e. 13*8=104). A larger value
shrinks the IPG (increasing bandwidth).
The reset value 12 leads to IEEE802.3ae
conformant behavior in both modes.
Note: WAN mode is only available in 10G
mode of operation.
18
48
CREDIT_TRIGGER
RW
Bit 0: Self-clearing Credit Reset. When
written with a 1, this bit will trigger a reset of
the RX application FIFO and will cause the
INIT_CREDIT value to be loaded into the
credit register. This bit should be
programmed before enabling the MAC and
after writing the initial credit value.
Bits 31:1 are unused and always set to ‘0’.
19
4C
INIT_CREDIT
RW
7:0: Specifies the initial/max credit value to
be loaded.
Bits 31:8 are unused
and always set to ‘0’.