Altera CPRI IP Core - Manual (Page 63)

Chapter 4: Functional Description 4–31
Auxiliary Interface
December 2013 Altera Corporation CPRI MegaCore Function
User Guide
The CPRI IP core implements the AUX receiver and AUX transmitter interfaces as
separate Avalon-ST interfaces. The AUX transmitter receives data to be transmitted on
the outgoing CPRI link, and the AUX receiver transmits data received from the
incoming CPRI link.
f For information about the Avalon-ST interface, refer to Avalon Interface Specifications .
AUX Receiver Module
The AUX receiver module transmits data that the CPRI IP core received on the CPRI
link to the outgoing AUX Avalon-ST interface. In addition, it provides detailed
information about the current state in the Rx CPRI frame synchronization state
machine. This information is useful for custom user logic, including frame
synchronization across hops in multihop configurations.
The AUX interface receiver module provides the following data and synchronization
lines:
■ cpri_rx_sync_state —when set, indicates that Rx, HFN, and BFN
synchronization have been achieved in CPRI receiver frame synchronization
■ cpri_rx_start —asserted for the duration of the first basic frame following the
offset defined in the CPRI_START_OFFSET_RX register
■ cpri_rx_rfp and cpri_rx_hfp —synchronization pulses for start of 10 ms radio
frame and start of hyperframe
■ cpri_rx_bfn and cpri_rx_hfn —current radio frame and hyperframe numbers
■ cpri_rx_x —index number of the current basic frame in the current hyperframe
■ cpri_rx_seq —index number of the current 32-bit word in the current basic frame
■ cpri_rx_aux_data —outgoing data port for sending data and control words
received on the CPRI link out on the AUX interface
The output synchronization signals are derived from the CPRI frame synchronization
state machine. These signals are all fields in the
aux_rx_status_data bus. For
additional information about the AUX receiver signals, refer to Table 6–3 on page 6–6 .