Altera Triple Speed Ethernet MegaCore Function User Manual Page 52
- Page / 223
- Table of contents
- BOOKMARKS
Rated. / 5. Based on customer reviews
Transmit FIFO Buffer Underflow
If the transmit FIFO buffer hits the almost-empty threshold during transmission and the FIFO buffer does
not contain the end-of-packet indication, the MAC function stops reading data from the FIFO buffer and
initiates the following actions:
1. The MAC function asserts the RGMII/GMII/MII error signals (tx_control/gm_tx_err/m_tx_err) to
indicate that the fragment transferred is not valid.
2. The MAC function deasserts the RGMII/GMII/MII transmit enable signals
(tx_control/gm_tx_en/m_tx_en) to terminate the frame transmission.
3. After the underflow, the user application completes the frame transmission.
4. The transmitter control discards any new data in the FIFO buffer until the end of frame is reached.
5. The MAC function starts to transfer data on the RGMII/GMII/MII when the user application sends a
new frame with an SOP.
Figure 4-7: Transmit FIFO Buffer Underflow
Figure illustrates the FIFO buffer underflow protection algorithm for gigabit Ethernet system.
[1]
[2]
[5]
[3]
[4]
ff_tx_data
ff_tx_sop
ff_tx_eop
ff_tx_rdy
ff_tx_wren
ff_tx_crc_fwd
ff_tx_err
ff_tx_septy
ff_tx_uflow
ff_tx_a_full
ff_tx_a_empty
gm_tx_err
gm_tx_en
gm_tx_d
GMII Transmit
Transmit FIFO
valid valid
valid
valid
Congestion and Flow Control
In full-duplex mode, the MAC function implements flow control to manage the following types of congestion:
• Remote device congestion—the receiving device experiences congestion and requests the MAC function
to stop sending data.
• Receive FIFO buffer congestion—when the receive FIFO buffer is almost full, the MAC function sends
a pause frame to the remote device requesting the remote device to stop sending data.
• Local device congestion—any device connected to the MAC function, such as a processor, can request
the remote device to stop data transmission.
Related Information
MAC Configuration Register Space on page 6-1
Functional Description
Altera Corporation
Send Feedback
UG-01008
Transmit FIFO Buffer Underflow
4-16
2014.06.30
- User Guide 1
- Contents 2
- Altera Corporation 10
- About This MegaCore Function 10
- Send Feedback 10
- High-Level Block Diagrams 10
- Figure 1-2: Multi-port MAC 11
- 10/100/1000-Mbps 12
- Ethernet MAC 12
- Optical Platform 14
- Copper Platform 14
- Release Information 18
- DescriptionItem 19
- Using the Parameter Editor 24
- Design Walkthrough 25
- Simulate the System 27
- Programming an FPGA Device 27
- Generated Files 28
- DescriptionFile Name 29
- Quartus II Pin 29
- Assignment 29
- Parameter Settings 30
- Ethernet MAC Options 31
- FIFO Options 33
- Timestamp Options 34
- PCS/Transceiver Options 34
- ParameterValueName 35
- Functional Description 37
- MAC Architecture 38
- MAC Interfaces 39
- MAC Transmit Datapath 40
- IP Payload Re-alignment 41
- Address Insertion 41
- Frame Payload Padding 41
- CRC-32 Generation 41
- Interpacket Gap Insertion 42
- MAC Receive Datapath 43
- ValueHash Code Bit 44
- Frame Type Validation 45
- Payload Pad Removal 46
- CRC Checking 46
- Length Checking 46
- Frame Writing 47
- IP Payload Alignment 47
- FIFO Buffer Thresholds 48
- Receive Thresholds 49
- Transmit Thresholds 51
- Congestion and Flow Control 52
- Magic Packets 53
- MAC Local Loopback 54
- MAC Error Correction Code 55
- MAC Reset 55
- PHY Management (MDIO) 56
- MDIO Connection 57
- MDIO Frame Format 57
- Gigabit Ethernet 58
- Programmable 10/100 Ethernet 59
- Transmit Operation 62
- Receive Operation 63
- SGMII Converter 64
- Auto-Negotiation 65
- SGMII Auto-Negotiation 66
- Ten-bit Interface 68
- PHY Loopback 69
- PHY Power-Down 69
- POWERDOWN 70
- 1000BASE-X PCS 70
- IEEE 1588v2 Features 72
- Time of Day 73
- IEEE 1588v2 Receive Datapath 74
- IEEE 1588v2 Frame Format 74
- 0..1500/9600 Octets 75
- 4 Octets 75
- CRC4 Octets 76
- 0..1500/9600 Octets Payload 76
- MAC Header 77
- UDP Header 77
- IP Header 77
- PTP Header 77
- Software Requirements 78
- Base Addresses 80
- IEEE 1588v2 Feature PMA Delay 100
- UG-01008 101
- 2014.06.30 101
- DescriptionR/WNameBit(s) 103
- DescriptionR/WNameBit 105
- 1000BASE-X 106
- Register Initialization 110
- Configuration Register Space 111
- Interface Signals 116
- Clock and Reset Signal 117
- MAC Control Interface Signals 118
- MAC Status Signals 118
- MAC Receive Interface Signals 119
- DescriptionBit 120
- DescriptionI/OName 123
- MII/GMII/RGMII Signals 124
- PHY Management Signals 125
- ECC Status Signals 126
- TBI Interface Signals 131
- Status LED Control Signals 132
- SERDES Control Signals 132
- Related Information 133
- SectionInterface Signal 135
- 1.25 Gbps Serial Interface 138
- Transceiver Native PHY Signal 138
- DescriptionWidthI/OSignal 141
- 1000BASE-X/SGMII PCS Signals 149
- PCS Control Interface Signals 150
- PCS Reset Signals 150
- SGMII Status Signals 152
- Avalon-ST Receive Interface 155
- IEEE 1588v2 Timestamp 162
- Design Considerations 163
- Configurations(1) 164
- Sharing Transceiver Quads 169
- Timing Constraints 171
- Recommended Clock Frequency 173
- 50–100CLK 174
- 1000BASE-X/SGMII PCS only 174
- 125REF_CLK 174
- 125TBI_TX_CLK 174
- 125TBI_RX_CLK 174
- Testbench 175
- Testbench Verification 176
- Testbench Configuration 177
- Test Flow 177
- Simulation Model 178
- Simulation Model Files 179
- Driver Architecture 180
- PHY Speed Bits 181
- Speed (Mbps) 181
- Using Jumbo Frames 183
- API Functions 184
- Constants 189
- DescriptionValueConstant 190
- Ethernet Frame Format 192
- Pause Frame Format 194
- Description 195
- XON_GENXOFF_GEN 195
- Simulation Parameters 196
- DefaultDescriptionParameter 197
- Test Configuration Parameters 198
- Time-of-Day (ToD) Clock 201
- ToD Clock Parameter Setting 202
- ToD Clock 203
- DescriptionR/WNameDword 205
- Adjusting ToD Clock Drift 206
- ToD Synchronizer 207
- ToD Synchronizer Block 208
- 32/6364/31516/6364/63Settings 209
- DescriptionValueName 209
- ToD Synchronizer Signals 210
- Packet Classifier 212
- Packet Classifier Signals 213
- Additional Information 217
- Document Revision History 218
- ChangesVersionDate 219
- How to Contact Altera 223
Related products and manuals for Measuring instruments Altera Triple Speed Ethernet MegaCore Function
(32 pages)© 2020, manymanuals.com. All rights reserved. | 0.643 s |
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals