Altera CPRI IP Core - Manual (Page 69)

Chapter 4: Functional Description 4–37
Media Independent Interface to an External Ethernet Block
December 2013 Altera Corporation CPRI MegaCore Function
User Guide
previous value. Figure 4–21 illustrates the behavior of the CPRI IP core signals in
response to the cpri_tx_sync_rfp pulse.
For more information about the relationships between the synchronization pulses and
numbers, refer to
Figure 4–17 on page 4–32 . For the mapping of data between the
AUX interface and the CPRI link, refer to Figure 4–18 on page 4–32 .
The cpri_tx_aux_data and cpri_tx_aux_mask signals are fields of the
aux_tx_mask_data bus. The other signals described in the preceding list are fields of
the aux_tx_status_data bus. For additional information about the AUX transmitter
signals, refer to Table 6–4 on page 6–7 .
Media Independent Interface to an External Ethernet Block
The media independent (MI) interface, or MII, allows the CPRI IP core to
communicate directly with an external Ethernet MAC block, replacing the internal
Ethernet MAC. You specify in the CPRI parameter editor whether to implement this
interface or to use the Ethernet MAC block available with the CPRI IP core. The two
options are mutually exclusive.
If you configure the CPRI IP core with the MII, you must implement the Ethernet
MAC block outside the CPRI IP core.
The MI interface is not a true media-independent interface, because it is clocked by
the
cpri_clkout clock (which drives the cpri_mii_txclk and cpri_mii_rxclk clock
signals directly), whose frequencies do not match the usual 2.5 MHz and 25 MHz
frequencies of the media-independent protocol specification. If you use this interface,
your external Ethernet block must communicate with the CPRI IP core synchronously
with the
cpri_mii_txclk and cpri_mii_rxclk clocks.
The MII supports the bandwidth described in the CPRI V5.0 Specification in Table 12,
Achievable Ethernet bit rates.
Figure 4–21. CPRI REC Master Response to cpri_tx_sync_rfp Resynchronization Pulse
cpri_clkout
cpri_tx_sync_rfp
cpri_tx_seq
cpri_tx_x
cpri_tx_hfn
cpri_tx_bfn
cpri_tx_hfp
cpri_tx_start
cpri_tx_rfp
5 6 7 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6
3 4 0
3 0
2 3