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readmemory

Read data from AXI4 memory-mapped slaves

Description

example

data = readmemory(mem,addr,size) reads size locations of data, starting from the address specified in addr, and incrementing the address for each word. By default, the output data type is uint32. addr, must refer to an AXI slave memory location controlled by the AXI master IP on your hardware board. The socAXIMaster object, mem, manages the connection between MATLAB® and the AXI master IP.

data = readmemory(mem,addr,size,Name,Value) reads size locations of 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 master 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 = socAXIMaster('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 master IP running on your hardware board, specified as an socAXIMaster 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 master IP on your hardware board.

Example: 'a4'

Number of memory locations to read, specified as an integer. By default, the function reads from a contiguous address block, incrementing the address for each operation. To turn off the address increment and read repeatedly from the same location, set the BurstType property to 'Fixed'.

When you specify a large operation size, such as reading a block of DDR memory, the object 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: readmemory(mem,140,10,'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 master reads a vector of data from contiguous memory locations, starting with the specified address. If this value is 'Fixed', the AXI master reads all data from the same address.

Data type assigned to the read data, specified as 'uint32', 'int8', 'int16', 'int32', 'uint8', 'uint16', 'single', or a numerictype object.

Output Arguments

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Read data, returned as scalar or vector depending on the value you specified for size. The function casts the data to the data type specified by the OutputDataType property.

Version History

Introduced in R2019a

See Also