Altera CPRI IP Core - Manual (Page 107)

Chapter 6: Signals 6–9
Auxiliary Interface Signals
December 2013 Altera Corporation CPRI MegaCore Function
User Guide
Extended Rx Status Signals
Table 6–5 lists the signals on the extended Rx status interface. All of these signals
report on the status of the CPRI receiver frame synchronization machine.
Table 6–5. Extended Rx Status Signals
Signal Direction Bits Description
extended_rx_status_data
[11:0]
Output
[11]
cpri_rx_los : CPRI receiver LOS indication (active high). This
bit reflects the value in the rx_los field of the CPRI_STATUS
register ( Table 7–5 on page 7–3 ).
[10:8]
cpri_rx_lcv : Current CPRI receiver 8B/10B line code violation
count in current clock cycle. This information enables CPRI link
debug when the control word does not appear or is malformed.
[7]
cpri_rx_hfn_state : When set, indicates that hyperframe
synchronization (HFN) has been achieved in CPRI receiver frame
synchronization.
[6]
cpri_rx_bfn_state : When set, indicates that basic frame
synchronization (BFN) has been achieved in CPRI receiver frame
synchronization.
[5]
cpri_rx_freq_alarm : Frequency alarm. When set, indicates a
frequency difference greater than four clock cycles between
cpri_clkout and the recovered received clock from the CPRI
receiver interface.
[4:2]
cpri_rx_cnt_sync : CPRI receiver frame synchronization state
machine state number. Tracks the number of the current state in
its state type. When the state machine is in state XACQ1, the
value of
cpri_rx_cnt_sync is 0; when the state is XACQ2,
cpri_rx_cnt_sync has value 1; when the state is XSYNC1,
cpri_rx_cnt_sync has value 0; and so on. Refer to
Figure 4–27 on page 4–56 .
[1:0]
cpri_rx_state : Indicates the type of state of the CPRI receiver
frame synchronization state machine. The following values are
defined:
00 - LOS state
01 - XACQ state
10 - XSYNC state
11 - HFNSYNC state
In the HFNSYNC state ( cpri_rx_state has value 0x3 and
cpri_rx_cnt_sync has value 0x1), Rx synchronization has
been achieved, except for initialization of the hyperframe and
basic frame numbers. You must wait for
cpri_rx_hfn_state
and cpri_rx_bfn_state to have value 1, indicating that the
hyperframe number and basic frame number are initialized.