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Transferring Data Using a Memory Item

Last Modified: February 27, 2020

Use a memory item to transfer data on an FPGA without respect to the sequence in which the data is written to memory.

What to Use

What to Do

Create the following diagram to transfer data between loops on an FPGA.

Customize the gray sections for your unique programming goals.

Define the data type, size, and latency of your locally scoped memory item using the Create Memory node. In this example, the Create Memory node defines the memory item properties to the following values:
  • Memory type is Block RAM
  • Read latency is 1 cycle
  • Read-only is disabled
Specify the address within the memory item where you write data from this clock domain. The code in this diagram generates one address per loop iteration in the series {0,1,2} so that the Write Memory node can write a value for each of the three cases in the Case Structure in this While Loop.

Capture or generate the data you write to memory during each loop iteration.

In this diagram, the Case Structure performs Square, Negate, and Increment operations on the value received from input value.

Use the memory reference from the Create Memory node to specify the memory item that the Write Memory node writes data samples to. For example, in this diagram, the Write Memory node writes the result of the square operation to address 0, writes the result of the negate operation to address 1, and writes the result of the increment operation to address 2.
Specify the address you read from this loop. The Case Selector, labeled operation, selects address 0 for Square, address 1 for Negate, and address 2 for Increment.
The Read Memory node waits until data from the specified address is read from the memory.
The Read Memory node returns an error if the specified address is greater than the size of the memory. Use the error out output to check if the output data is valid. Use the output data to perform subsequent operations.

Troubleshooting

If the memory item returns unexpected data, verify that the input addresses for the Read Memory and Write Memory nodes are correct.

Examples

Search within the programming environment to access the following installed example: Memory.


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