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writememory

Write data to AXI4 memory-mapped locations

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Syntax

writememory(mem,addr,data)
writememory(mem,addr,data,Name,Value)

Description

writememory(mem,addr,data) writes all words specified in data, starting from the address specified in addr, and then incrementing the address for each word. addr, must refer to an AXI slave memory location controlled by the AXI manager IP on your hardware board. The socAXIManager object, mem, manages the connection between MATLAB® and the AXI manager IP.

example

writememory(mem,addr,data,Name,Value) writes all words specified in data, starting from the address specified in addr, with additional options specified by one or more Name,Value pair arguments.

Examples

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For this example, you must have a design running on a hardware board connected to the MATLAB host machine.

Create a MATLAB AXI manager object. The object connects with the hardware board and confirms that the IP is present. You can create the object with a vendor name or an socHardwareBoard object.

mem = socAXIManager('Xilinx');

Write and read one or more addresses with one command. By default, the functions auto-increment the address for each word of data. For instance, write ten addresses, then read the data back from a single location.

writememory(mem,140,[10:19])
rd_d = readmemory(mem,140,1)

rd_d =

  uint32

   10

Now, read the written data from ten locations.

rd_d = readmemory(mem,140,10)
rd_d =

  1×10 uint32 row vector

   10   11   12   13   14   15   16   17   18   19

Set the BurstType property to 'Fixed' to turn off the auto-increment and access the same address multiple times. For instance, read the written data ten times from the same address.

rd_d = readmemory(mem,140,10,'BurstType','Fixed')
rd_d =

  1×10 uint32 row vector

   10   10   10   10   10   10   10   10   10   10

Write incrementing data ten times to the same address. The final value stored in address 140 is 29.

writememory(mem,140,[20:29],'BurstType','Fixed')
rd_d = readmemory(mem,140,10)
rd_d =

  1×10 uint32 row vector

   29   11   12   13   14   15   16   17   18   19

Alternatively, specify the address as a hexadecimal string. To cast the read data to a data type other than uint32, use the OutputDataType property.

writememory(mem,'1c',[0:4:64])
rd_d = readmemory(mem,'1c',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 are done accessing the board, release the JTAG connection.

release(mem)

Input Arguments

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JTAG connection to AXI manager IP running on your hardware board, specified as an socAXIManager object.

Starting address for read operation, specified as an integer or a hexadecimal character vector. The function casts the address to uint32 data type. The address must refer to an AXI slave memory location controlled by the AXI manager IP on your hardware board.

Example: 'a4'

Data words to write, specified as a scalar or a vector. By default, the function writes the data to a contiguous address block, incrementing the address for each operation. To turn off the address increment and write each data value to the same location, set the BurstType property to 'Fixed'.

Before sending the write request to the board, the function casts the input data to uint32 or int32 data type. The data type conversion follows these rules:

  • If the input data type is double, then the data is cast to int32 data type.

  • If the input data type is single, then the data is cast to uint32 data type.

  • If the bit width of the input data type is less than 32 bits, then the data is sign-extended to 32 bits.

  • If the bit width of the input data type is longer than 32 bits, then the data is cast to int32 or uint32 data type, matching the signedness of the original data type.

  • If the input data is a fixed-point data type, then the function writes the stored integer value of the data.

When you specify a large operation size, such as writing a block of DDR memory, the function automatically breaks the operation into multiple bursts, using the maximum supported burst size. The maximum supported burst size is 256 words.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: writememory(mem,140,[20:29],'BurstType','Fixed')

AXI4 burst type, specified as the comma-separated pair consisting of 'BurstType' and either 'Increment' or 'Fixed'. If this value is 'Increment', the AXI manager writes a vector of data from contiguous memory locations, starting with the specified address. If this value is 'Fixed', the AXI manager writers all data from the same address.

Version History

Introduced in R2019a

See Also