1. Introduction
The SAMA5D3 series is a member of the Atmel® microprocessor family which is based
on the ARM® Cortex™-A5 processor core.
This Application Note outlines the Gigabit Ethernet function embedded on SAMA5D3
Series.
2. Associated Documentation
Before going further into this document, please refer to the latest documentation for the
corresponding SAMA5D3 devices avai lab le on the Atmel ® web s i te a t
http//:www.atmel.com.
z SAMA5D3 Series Datasheet: lit° 11121
z SAMA5D3-EK User Guide: lit° 11180
3. Gigabit Ethernet Implementation on SAMA5D3 Series
z Compatible with IEEE Standard 802.3
z 10, 100 and 1000 Mbit/s Operation
z Full and Half Duplex Operation at All Three Speeds of Operation
z Statistics Counter Registers for RMON/MIB
z MII/GMII/RGMII Interface to the Physical Layer
z RMII is Not Supported
z Integrated Physical Coding
z Direct Memory Access (DMA) Interface to External Memory
z Support for up to Eight Priority Queues in DMA
z Programmable Burst Length and Endianism for DMA
z Interrupt Generation to Signal Receive and Transmit Completion, or Errors
z Automatic Pad and Cyclic Redundancy Check (CRC) Generation on Transmitted
Frames
z Frame Extension and Frame Bursting at 1000 Mbit/s in Half Duplex Mode
z Automatic Discard of Frames Received with Errors
Application Note
AT91SAM ARM-based Embedded MPU
Gigabit Ethernet Implementation on SAMA5D3 Series
11164A–ATARM–31-Jan-13
z Receive and Transmit IP, TCP and UDP Checksum Offload. Both IPv4 and IPv6
Packet Types Supported
z Address Checking Logic for Four Specific 48-bit Addresses, Four Type IDs,
Promiscuous Mode, Hash Matching of Unicast and Multicast Destination
Addresses and Wake-on-LAN
z Management Data Input/Output (MDIO) Interface for Physical Layer
Management
z Support for Jumbo Frames up to 10240 Bytes
z Full Duplex Flow Control with Recognition of Incoming Pause Frames and Hardware Generation of Transmitted
Pause Frames
z Half Duplex Flow Control by Forcing Collisions on Incoming Frames
z Support for 802.1Q VLAN Tagging with Recognition of Incoming VLAN and Priority Tagged Frames
z Support for 802.1Qbb Priority-Based Flow Control
z Programmable Inter Packet Gap (IPG) Stretch
z Recognition of IEEE 1588 PTP Frames
z IEEE 1588 Time Stamp Unit (TSU)
z Support for 802.1AS Timing and Synchronization
4. Signal Description and Connection
The GMAC includes the following signal interfaces:
z GMII, MII, and RGMII to an external PHY
z MDIO interface for external PHY management
z Slave APB interface for accessing GMAC registers
z Master AHB interface for memory access
Table 4-1. GMAC Connections in Different Modes
Signal Name Function MII GMII RGMII
GTXCK Transmit Clock or Reference Clock TXCK Not Used TXCK
G125CK 125 MHz input Clock Not Used 125 MHz Ref Clk 125 MHz Ref Clk
G125CKO 125 MHz output Clock Not Used TXCK Not Used
GTXEN Transmit Enable TXEN TXEN TXCTL
GTX[7..0] Transmit Data TXD[3:0] TXD[7:0] TXD[3:0]
GTXER Transmit Coding Error TXER TXER Not Used
GRXCK Receive Clock RXCK RXCK RXCK
GRXDV Receive Data Valid RXDV RXDV Not Used
GRX[7..0] Receive Data RXD[3:0] RXD[7:0] RXD[3:0]
GRXER Receive Error RXER RXER RXCTL/RXDV
GCRS Carrier Sense and Data Valid CRS CRS Not Used
GCOL Collision Detect COL COL Not Used
GMDC Management Data Clock MDC MDC MDC
GMDIO Management Data Input/Output MDIO MDIO MDIO
2Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
Figure 4-1. Connection between Ethernet PHY and Ethernet MAC in the MII/GMII Mode.
Figure 4-2. Connection between Ethernet PHY and Ethernet MAC in the RGMII Mode
3Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
5. MII: Media Independent Interface
The MII bus (standardized by IEEE 802.3) is a generic bus that connects different types of PHYs to the same network
controller (MAC). The network controller may interact with any PHY using the same hardware interface, independent of
the media the PHYs are connected to. The MII transfers data using 4bit words (nibble) in each direction, clocked at 25
MHz to achieve 100 Mbit/s speed.
The basic operation of data transmission is that the enable signal (TXEN) is set active to indicate start of frame and until
it is completed. Then the clock signal (TXCLK) is set active for every group of bits (TXD[3:0]), at 2.5 MHz for 10 Mbit/s
mode and 25 MHz for 100 Mbit/s mode. When the reception is valid, the RXDV signal goes active when the frame starts
and throughout the frame duration. Then the clock signal (RXCLK) goes active for every group of bits (RXD[3:0]). For the
shortest possible frame this means ~130 clocks. Any frame transferred begins with sync bits before the data payload. At
power-up, the PHY adapts to whatever it is connected to, unless you alter settings via the MDIO interface.
The following table describes MII signals:
Note: 1. Direction is defined from the chip side: IN = PHY to MAC, OUT = MAC to PHY.
Table 5-1. MII Signals
Channel Signal Direction(1) Description
PHY to MAC
TXCK IN Transmit clock (generated by the PHY): 2.5 MHz for 10 Mbit/s and 25 MHz for 100 Mbit/s
TXD[4:0] OUT Data to be transmitted
TXEN OUT Transmitter enable
TXER OUT Transmitter error (used to corrupt a packet)
MAC to PHY
RXCK IN Received clock
RXD[4:0] IN Received data
RXDV IN Signifies that received data is valid
RXER IN Signifies that received data has errors
Carrier and
Collision
CRS IN Carrier Sense (half-duplex connections only)
COL IN Collision Detect (half-duplex connections only)
PHY
Management
MDCK OUT
MDIO INOUT
4Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
6. GMII: Gigabit Media Independent Interface
GMII is an addendum to MII interface. It has been added to handle Gigabit Ethernet 1000 Mbit/s transfer rate. GMII does
not replace MII, as it is not specified to work with 10 and 100 Mbit/s transfer rates. Therefore, for 10 or 100 Mbit/s transfer
rates, MII interface is used instead of GMII.
One of the major differences between MII and GMII is that TX clock (MAC to PHY clock) is not provided by the PHY
anymore, it is the MAC that provides the clock. Then each of RX and TX channels provides its own clock. This prevents
timing closure issues, as Gigabit mode frequency clock is 125 MHz (4 ns period). Four additional bits have been added
on Data signals in order to reach the 1000 Mbit/s rate (frequency is 5 times the one of 100 Mbit/s rate, and data bus width
is doubled, then the factor of 10 is reached).
The following table describes GMII signals:
Note: 1. Direction is defined from the chip side: IN = PHY to MAC, OUT = MAC to PHY.
Table 6-1. GMII Signals
Channel Signal Direction(1) Description
PHY to MAC
GTXCK OUT Transmit clock for 1000 Mbit/s: 125 MHz
TXCK IN
Transmit clock (generated by the PHY for MII
compatibility): 2.5 MHz for 10 Mbit/s and 25 MHz for
100 Mbit/s
TXD[7:0] OUT Data to be transmitted (4 bits more than MII)
TXEN OUT Transmitter enable
TXER OUT Transmitter error (used to corrupt a packet)
MAC to PHY
RXCK IN Received clock
RXD[7:0] IN Received data (4 bits more than MII)
RXDV IN Signifies that received data is valid
RXER IN Signifies that received data has errors
Carrier and
Collision
CRS IN Carrier Sense (half-duplex connections only)
COL IN Collision Detect (half-duplex connections only)
PHY
Management
MDCK OUT SMI clock
MDIO INOUT SMI data
5Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
7. RGMII: Reduced Gigabit Media Independent Interface
RGMII uses half the number of data pins used in the GMII interface. This reduction is achieved by clocking data on both
the rising and the falling edges of the clock, and by eliminating non-essential signals (carrier sense and collision
indication).
Thus RGMII consists only of: RXC, RD[3:0], RX_CTL, TXC, TXD[3:0], and TX_CTL (12 pins, as opposed to 24 pins for
GMII).
Unlike MII, the transmit clock signal is always provided by the MAC on the TXC line, rather than being provided by the
PHY for 10/100 Mbit/s operation and by the MAC at 1000 Mbit/s.
RGMII supports Ethernet speeds of 10 Mbit/s, 100 Mbit/s and 1000 Mbit/s.
The following table describes RGMII signals:
Note: 1. Direction is defined from the chip side: IN = PHY to MAC, OUT = MAC to PHY.
Table 7-1. RGMII Signals
Channel Signal Direction(1) Description
Clock GTXCK IN 125 MHz reference clock
PHY to MAC
TX_CLK /
GTXCKO OUT
Transmit clock (generated by the MAC with master
clock GTXCK): 2.5 MHz for 10 Mbit/s, 25 MHz for
100 Mbit/s and 125 MHz for 1000 Mbit/s
TXD[3:0] OUT Data to be transmitted
TXCTL OUT Transmitter enable / Transmitter error
MAC to PHY
RXC IN Received clock: 2.5 MHz for 10 Mbit/s, 25 MHz for 100 Mbit/s and 125 MHz for 1000 Mbit/s
RXD[3:0] IN Received data
RXCTL IN Signifies that received data has errors
PHY
Management
MDCK OUT SMI clock
MDIO INOUT SMI data
6Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
8. Routing Considerations
The user should refer to the design and layout guidelines of the PHY provider.
8.1 SAMA5D3 Example
This example shows how SAMA5D3-EK connects to KSZ9021GN PHY.
The functional mode is defined by the software. PHY is configured to operate in GMII, RGMII or MII mode, according to
the chosen hardware connection.
Figure 8-1. Functional Connection.
7Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
Figure 8-2. Schematics Extract of SAMA5D3-EK
8Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
Revision History
In the table that follows, the most recent version of the document appears first.
“rfo” indicates changes requested during the document review and approval loop.
Doc. Rev Comments
Change Request
Ref.
11164A First issue.
9Gigabit Ethernet Implementation on SAMA5D3 Series [APPLICATION NOTE]
11164A–ATARM–31-Jan-13
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1. Introduction
2. Associated Documentation
3. Gigabit Ethernet Implementation on SAMA5D3 Series
4. Signal Description and Connection
5. MII: Media Independent Interface
6. GMII: Gigabit Media Independent Interface
7. RGMII: Reduced Gigabit Media Independent Interface
8. Routing Considerations
8.1 SAMA5D3 Example
Revision History
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