Mgt

Tutorial Overview

In the last tutorial we implemented the embedded Tri-mode Ethernet MAC and tested it by looping back Ethernet packets and monitoring them with Wireshark. In this tutorial, we will again implement the EMAC but this time we will link it to an Aurora core, to implement an Aurora to Ethernet Bridge. With the bridge, we can link two PCs as shown in the diagram below.

To connect the EMAC and Aurora cores we have to use two FIFOs to cross clock domains. The EMAC has a user clock of 125MHz and a data interface of 8 bits, while the Aurora core will have a user clock of 62.5MHz and a data interface of 16 bits. The diagram below illustrates the connections between the EMAC and Aurora core and the clock domain crossing FIFOs.

Overview In this tutorial we will create a peripheral containing the Aurora core to implement a high speed serial transceiver with a RocketIO MGT. It will be an improved version of the Aurora transceiver developed in the tutorial titled Create an Aurora Transceiver. The improvement is achieved by connecting the peripheral to the PLB rather than the OPB, which allows much faster data transfer by virtue of a wider bus and Direct Memory Access capability.

Overview In this tutorial we will create a peripheral containing the Aurora core to implement a high speed serial transceiver with a RocketIO MGT. The peripheral can be used to connect two XUPV2P boards using the SATA connectors and transfer data between them at 1.5Gbps. To test the design using only one XUPV2P board, we will instantiate two Aurora peripherals, assign them to different RocketIO MGTs and place a SATA cable between them to create a loop-back connection. The PowerPC will transfer data between the two Aurora peripherals simply by reading and writing to the read and write FIFOs. To test the design, the test application will write data to the write FIFO of the first Aurora peripheral and read it back from the read FIFO of the second Aurora peripheral. The Aurora peripheral will also have outputs indicating the status of the link. These outputs will be connected to the LEDs on the XUPV2P board.

Overview

In this tutorial we will use a RocketIO MGT for possibly its simplest application, a programmable oscillator. This can be achieved by feeding the MGT with a repetitive data pattern (e.g. “10101010101010101010”). By changing the data pattern we can adjust the output frequency and duty cycle.

Figure: The Oscillator peripheral

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The diagram above illustrates the oscillator peripheral. In it we use 4 registers to store a 4 x 32 bit repeating pattern to be fed to the RocketIO primitive (GT_CUSTOM). Note that we could have used any number of registers to store the pattern. In our user_logic.vhd file we instantiate the GT_CUSTOM and create a counter which we use for loading the GT_CUSTOM. The counter counts from 1 to 4 and each time it loads the corresponding register contents into the GT_CUSTOM for transmission.