SmartDesign MSS
Ethernet MAC Configuration
Introduction
The SmartFusion Microcontroller Subsystem (MSS) provides one Ethernet MAC hard peripheral.
The actual behavior of the Ethernet MAC must be defined at the application level using the SmartFusion
MSS MAC Driver provided by Actel.
In this document, we describe how you can enable the MSS MAC instance and select whether the
Ethernet MAC interface is connected to dedicated MSS I/Os or the FPGA fabric.
For more details about the MSS MAC hard peripheral, please refer to the Actel SmartFusion
Microcontroller Subsystem User’s Guide.
Configuration Options
Enabling/Disabling the MAC Instance. On the MSS canvas, you need to enable (default) or disable the MAC instance based on whether it is being used into your current application. If disabled, the MAC instance is held in reset (lowest power state) after the Actel system boot code is executed.
Connectivity Options. When using the A2F200M3F device, the Ethernet MAC, when enabled, can only be connected to dedicated MSS I/Os. When using the A2F500M3G device, you can choose to connect the MAC peripheral to dedicated MSS I/Os or the FPGA fabric. In all cases, the MAC connectivity is automatically configured by the Actel system boot code. Note that MSS I/Os allocated to the MAC instance are available to connect to the FPGA fabric if the MAC instance is disabled. Refer to the MSS I/O Configuration document for more details. To use the MAC FPGA ports (if that option is selected), you need to manually promote to the top level the FABRIC group port present on the MSS MAC instance. You can then use the FABRIC MAC ports in the next level of hierarchy.
Ethernet MAC Clock Selection. If you enable the MAC peripheral on the MSS configurator canvas the MAC clock is automatically selected (read-only) in the Clock configurator. Using the MSS Clock configurator you need to select one of the following MAC clock sources.
- The external 10/100 clock (MAC_CLK pin) on the SmartFusion device.
- A clock generated in the MSS Clock Conditioning Circuit (MSS_CCC).
Port Description
Table 1: MSS I/O Connectivity Options
| Port Name | Port Group | Direction | PAD? | Description |
| RXER | PADs | In | Yes | Receive error. If RX_ER is asserted during Ethernet MAC reception, the frame is received and status of the frame is updated with RX_ER. |
| CRSDV | PADs | In | Yes | Carrier sense and receive data valid. This signal must be asserted by the PHY when either a receive or transmit medium is non-idle. The PHY device should assert MAC_CRSDV when valid data is provided on the RXD signal. |
| MDIO | PADs | Inout | Yes | RMII management data input and output. The state of the input signal can be checked by reading the CSR9.19 bit. The output signal is driven by the CSR9.18 bit. |
| RXD[1:0] | PADs | In | Yes | Receive data recovered and decoded by PHY. The RXD[0] signal is the least significant bit. |
| TXEN | PADs | Out | Yes | Transmit enable. When asserted, indicates valid data for the PHY on the TXD port. |
| MDC | PADs | Out | Yes | RMII management clock = 25 MHz. This signal is driven by the CSR9.16 bit. |
| TXD[1:0] | PADs | Out | Yes | Transmit data. The TXD[0] signal is the least significant bit. |
Table 2: FPGA Fabric Connectivity Options
| Port Name | Port Group | Direction | PAD? | Description |
| F2M_RXER | FABRIC | In | No | Receive error. If RX_ER is asserted during Ethernet MAC reception, the frame is received and status of the frame is updated with RX_ER. |
| F2M_CRSDV | FABRIC | In | No | Carrier sense and receive data valid. This signal must be asserted by the PHY when either a receive or transmit medium is non-idle. The PHY device should assert MAC_CRSDV when valid data is provided on the RXD signal. |
| F2M_MDI | FABRIC | In | No | RMII management data input. The state of the input signal can be checked by reading the CSR9.19 bit |
| Port Name | Port Group | Direction | PAD? | Description |
| M2F_MDIO | FABRIC | Out | No | RMII management data output. The output signal is driven by the CSR9.18 bit. |
| M2F_MDEN | FABRIC | Out | No | RMII management data output enable. |
| F2M_RXD[1:0] | FABRIC | In | No | Receive data recovered and decoded by PHY. The RXD[0] signal is the least significant bit. |
| M2F_TXEN | FABRIC | Out | No | Transmit enable. When asserted, indicates valid data for the PHY on the TXD port. |
| M2F_MDC | FABRIC | Out | No | RMII management clock = 25 MHz. This signal is driven by the CSR9.16 bit. |
| M2F_TXD[1:0] | FABRIC | Out | No | Transmit data. The TXD[0] signal is the least significant bit. |
Notes:
- PAD ports are automatically promoted to top throughout the design hierarchy.
- Non-PAD ports must be promoted manually to the top level from the MSS configurator canvas to be available as the next level of hierarchy.
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Documents / Resources
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Actel SmartFusion Microcontroller Subsystem (MSS) [pdf] User Guide SmartFusion Microcontroller Subsystem MSS, SmartFusion, Microcontroller Subsystem MSS, Subsystem MSS |
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Actel SmartFusion Microcontroller Subsystem (MSS) [pdf] User Guide SmartFusion Microcontroller Subsystem MSS |
