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Release JTAG or Ethernet cable resource



    release(mem) releases the JTAG cable or Ethernet cable resource, depending on the interface that you use.

    • When you use a JTAG interface, the function releases the JTAG cable resource, freeing the cable for use to reprogram the FPGA. After initialization, the AXI manager object, mem, holds the JTAG cable resource, and other programs cannot access the JTAG cable. While you have an active AXI manager object, FPGA programming over JTAG fails. Call the release function before reprogramming the FPGA.

    • When you use an Ethernet interface, the function closes the Ethernet communications channel and clears the associated resources. During the creation of AXI manager object mem, the object initializes a communication stream to enable the exchange of data between the host computer and the target processor. Call the release function when you no longer need to access the board.


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    This example shows how to read and write the memory locations on a Xilinx® FPGA board from MATLAB®.

    Before you can use this example, you must have a design running on an FPGA board connected to the MATLAB host machine. The FPGA design must include an AXI manager IP that is customized for your FPGA vendor. The support package installation includes this IP. To include the IP in your project, see the Access FPGA Memory Using JTAG-Based AXI Manager example.

    Create an AXI manager object. The object connects MATLAB with the FPGA board and confirms that the IP is present.

    mem = aximanager('Xilinx')
    mem =
       aximanager with properties:
                Vendor: 'Xilinx'
         JTAGCableName: 'auto'

    Write 10 addresses and then read data from a single location. By default, these functions auto-increment the address for each word of data.

    rd_d = readmemory(mem,140,1)
    rd_d =

    Read data from 10 locations.

    rd_d = readmemory(mem,140,10)
    rd_d =
       1x10 uint32 row vector
        10   11   12   13   14   15   16   17   18   19

    Read data 10 times from the same address by specifying that the AXI manager read all data from the same address (disabling auto-incrementation).

    rd_d = readmemory(mem,140,10,'BurstType','Fixed')
    rd_d =
       1x10 uint32 row vector
        10   10   10   10   10   10   10   10   10   10

    Write data 10 times to the same address. In this case, the final value stored in address 140 is 29.

    rd_d = readmemory(mem,140,10)
    rd_d =
       1x10 uint32 row vector
        29   11   12   13   14   15   16   17   18   19

    Specify the address as a hexadecimal value. Specify for the function to cast the read data to a data type other than uint32.

    rd_d = readmemory(mem,0x1c,16,'OutputDataType',numerictype(0,6,4))
    rd_d =
       Columns 1 through 10
              0    0.2500    0.5000    0.7500    1.0000    1.2500 ...
                             1.5000    1.7500    2.0000    2.2500
       Columns 11 through 16
         2.5000    2.7500    3.0000    3.2500    3.5000    3.7500
               DataTypeMode: Fixed-point: binary point scaling
                 Signedness: Unsigned
                 WordLength: 6
             FractionLength: 4

    When you no longer need to access the board, release the JTAG connection.


    Input Arguments

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    Connection to a JTAG-based AXI manager IP or to an Ethernet-based AXI manager IP, specified as an aximanager object.

    Version History

    Introduced in R2017a