Altera CPRI IP Core Manuel d'utilisateur Page 205
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- Table des matières
- MARQUE LIVRES
Noté. / 5. Basé sur avis des utilisateurs
Appendix E: Delay Measurement and Calibration E–27
Multi-Hop Delay Measurement
December 2013 Altera Corporation CPRI MegaCore Function
User Guide
Multi-Hop Delay Measurement
In a multihop system, you must combine the delays between and through the
different CPRI masters and CPRI RE slaves to determine the round-trip delay.
Round-Trip Delay Calculation
The value in the
rx_round_trip_delay
field of the
CPRI_ROUND_DELAY
register is
meaningful only in CPRI REC and RE masters. It records the round-trip delay for the
current hop only, as shown in Figure E–1 on page E–2.
To determine the round-trip delay of a full multihop system, you must add together
the values in the
CPRI_ROUND_DELAY
registers of the REC and RE masters in the system,
plus the delays through the external routers, and subtract the loopback delay from all
the hops except the final hop. Use the following calculation, based on the labels in
Figure E–2 on page E–2:
Round-trip delay =
rx_round_trip_delay
(hop i) + (TBdelayUL + TBdelayDL)(j)
– n
where the REC and RE masters in the configuration are labeled i=0,1,...,n and the
routing layers in the configuration, and their uplink and downlink delays, are labeled
j=0,1,...,(n-1).
As the equation shows, you must omit the loopback delay of one
cpri_clkout
cycle
from the single-hop calculation for all but the final pair of CPRI link partners. The
loopback delay is only relevant at the turnaround point of the full multihop path.
Round-Trip Cable Delay Calculation
To determine the local round-trip cable delay at each hop, use the method described
in “Round-Trip and Cable Delay Calculation Examples”, for the REC or RE master
and the RE slave at the current hop. Half of the resulting value is assumed to be the
cable delay in each direction at the current hop.
The round-trip cable delay is the sum of all the local round-trip cable delays in the
multihop path.
- User Guide 1
- CPRI MegaCore Function 1
- Contents 3
- Chapter 5. Testing Features 4
- ContentsContents v 5
- General Description 8
- CPRI IP Core Features 10
- Device Family Support 11
- MegaCore Verification 12
- Release Information 14
- Installation and Licensing 15
- OpenCore Plus Evaluation 16
- 2. Getting Started 17
- Specifying Parameters 18
- Simulation Files 19
- Simulating the Design 20
- Supporting the Transceivers 21
- Specifying Constraints 21
- 3. Parameter Settings 25
- Operation Mode Parameter 26
- Line Rate Parameter 26
- Enable Autorate Negotiation 27
- Rx Elastic Buffer Depth 27
- Include MAC Block 28
- Include HDLC Block 29
- Mapping Mode 29
- Application Layer Parameters 30
- Words” on page 4–42 32
- 4. Functional Description 33
- Architecture Overview 34
- CPRI IP Core Clocks 35
- Clocking Structure 36
- Notes to Table 4–2: 42
- Reset Requirements 43
- MegaCore 44
- Function 44
- MAP Interface Mapping Modes 45
- Basic AxC Mapping Mode 46
- MAP Interface 47
- Note to Table 4–5: 49
- Note to Table 4–6: 49
- Advanced AxC Mapping Modes 50
- MAP Receiver Interface 50
- Notes to Table 4–7: 51
- MAP Receiver in FIFO Mode 52
- MAP Transmitter Interface 56
- Notes to Table 4–10: 57
- MAP Transmitter in FIFO Mode 58
- Auxiliary Interface 62
- AUX Receiver Module 63
- Avalon-ST 32-bit interface 64
- AUX Transmitter Module 66
- Note to Figure 4–19: 67
- MII Transmitter 70
- MII Receiver 71
- CPU Interface 73
- Control Word Order 78
- Transmitting Ethernet Traffic 80
- Receiving Ethernet Traffic 81
- Accessing the HDLC Channel 82
- Note to Table 4–15: 83
- Features 84
- Physical Layer Architecture 84
- Receiver 85
- High-Speed Transceiver 86
- Rx Elastic Buffer 86
- Descrambling 87
- Frame Synchronization 87
- Alarm Indications 88
- Reset Control Word 89
- Transmitter 90
- Scrambling 91
- Tx Elastic Buffer 91
- External Loopback 93
- CPRI IP Core 93
- Internal Reverse Loopback 94
- Physical Layer Loopback Mode 94
- (1) (2) (3) 96
- MAP Receiver Signals 99
- 6–2 Chapter 6: Signals 100
- MAP Interface Signals 100
- MAP Transmitter Signals 101
- 6–4 Chapter 6: Signals 102
- Auxiliary Interface Signals 103
- AUX Receiver Signals 104
- AUX Transmitter Signals 105
- 6–8 Chapter 6: Signals 106
- Extended Rx Status Signals 107
- CPRI MII Receiver Signals 108
- CPRI MII Transmitter Signals 108
- CPU Interface Signals 109
- CPRI Data Signals 110
- Layer 1 Error Signal 111
- Autorate Negotiation Signals 111
- 6–14 Chapter 6: Signals 112
- Physical Layer Signals 112
- Transceiver Signals 113
- 6–16 Chapter 6: Signals 114
- Note to Table 6–14: 115
- 6–18 Chapter 6: Signals 116
- 7. Software Interface 117
- Note to Table 7–5: 119
- CPRI_HW_RESET 123
- register, refer to “Reset 123
- Requirements” on page 4–11 123
- Note to Table 7–13: 124
- Note to Table 7–16: 125
- Note to Table 7–17: 126
- Note to Table 7–20: 126
- Notes to Table 7–21: 127
- Notes to Table 7–28: 130
- Notes to Table 7–29: 130
- Note to Table 7–32: 133
- Note to Table 7–33: 133
- Note to Table 7–34: 133
- Note to Table 7–35: 134
- Note to Table 7–36: 134
- Notes to Table 7–37: 135
- Notes to Table 7–38: 135
- Notes to Table 7–39: 136
- Notes to Table 7–40: 136
- Note to Table 7–45: 137
- Ethernet Registers 138
- HDLC Registers 143
- Note to Figure 8–1: 150
- Test Sequence 151
- Running the Testbench 153
- A. Initialization Sequence 155
- Negotiation 157
- Notes for Figure B–1: 158
- Running Autorate Negotiation 159
- Notes to Table C–3: 167
- D. Advanced AxC Mapping Modes 173
- Fifteen-Bit Width Mode 175
- Sixteen-Bit Width Mode 176
- Note to Figure D–2: 177
- Delay Requirements 179
- RE SlaveREC Master 180
- Rx Path Delay 181
- Most CPRI IP Core Variations 181
- Single-Hop Delay Measurement 182
- Notes to Table E–1: 183
- Notes to Table E–2: 184
- Notes to Table E–3: 186
- Arria V GT 9.8 Gbps 188
- Notes to Table E–4: 189
- Tx Path Delay 190
- Note to Table E–6: 192
- T_txv_TX 194
- in Figure E–1 on page E–2 194
- Round-Trip Delay 196
- Round-Trip Cable Delay 196
- Families 202
- Round-Trip Delay Calculation 205
- Multi-Hop Delay Measurement 206
- Additional Information 213
- Document Revision History 214
- How to Contact Altera 218
- Typographic Conventions 218
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