Altera CPRI IP Core - Manual (Page 50)

4–18 Chapter 4: Functional Description
MAP Interface
CPRI MegaCore Function December 2013 Altera Corporation
User Guide
This value must be no larger than the number of bits in the IQ data block. The number
of bits in an IQ data block depends on the CPRI line rate, as shown in
Table 4–5 and
Table 4–6 .
1 If the combination of CPRI line rate, map_n_ac value, and map_ac value requires more
data bits than the number of data bits that fit in the IQ data block, the data for the first
active data channels is transferred correctly, but the data for data channels beyond the
number indicated in
Table 4–5 or Table 4–6 is not transferred correctly.
The following CPRI IP core registers are ignored in basic mapping mode:
■ CPRI_MAP_TBL_CONFIG register ( Table 7–33 on page 7–17 )
■ CPRI_MAP_TBL_INDEX register ( Table 7–34 on page 7–17 )
■ CPRI_MAP_TBL_RX register ( Table 7–35 on page 7–17 )
■ CPRI_MAP_TBL_TX register ( Table 7–36 on page 7–18 )
Advanced AxC Mapping Modes
The CPRI IP core provides advanced AxC mapping modes to support the following
mapping methods from the CPRI V4.2 Specification:
■ Method 1: IQ Sample Based, described in Section 4.2.7.2.5 of the CPRI V4.2
Specification.
■ Method 3: Backward Compatible, described in Section 4.2.7.2.7 of the CPRI V4.2
Specification.
In the advanced mapping modes, different data channels can use different sample
rates, and the sample rates need not be integer multiples of 3.84 MHz. However, all
data channels use the same sample width.
Your CPRI IP core implements one of the advanced AxC mapping modes when you
configure and program your CPRI IP core in any of the following ways:
■ If you select Advanced 1, Advanced 2, or Advanced 3 as the value for Mapping
mode(s)
in the CPRI parameter editor.
■ If you select All as the value for Mapping mode(s) in the CPRI parameter editor
and you program the
map_mode field of the CPRI_MAP_CONFIG register with the
value of 2’b01, 2’b10, or 2’b11.
For more information about the advanced AxC mapping modes in the Altera CPRI IP
core, refer to
Appendix D, Advanced AxC Mapping Modes . For information about
how to program the individual advanced mapping modes, refer to Table 4–4 on
page 4–13 .
MAP Receiver Interface
The CPRI IP core MAP receiver interface presents the IQ data that the CPRI IP core
unloads from the CPRI frame received on the CPRI link. The MAP receiver
implements an Avalon-ST interface protocol. Refer to
“MAP Receiver Signals” on
page 6–1 for details of the interface communication signals.