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# 1.32 XDMAC Memory Transfer

This example application shows how to use the XDMAC peripheral to do a memory to memory transfer and illustrates the usage of burst size to reduce the transfer time.

## Description

The application uses the XDMAC peripheral to transfer data from source buffer to destination buffer with burst sizes of 1 and 16. The number of cycles taken for the transfer is measured using the Periodic Interval Timer (PIT) to illustrate how the burst size helps to reduces the transfer time.

This example also demonstrates cache maintenance operation by cleaning and invalidating cache for the buffers located in cacheable memory. The buffers are aligned to cache line and its size is an integer multiple of the cache line size. Cache line(s) for source buffer range is cleaned before submitting a transfer request to DMA to load the latest data in the cache to the RAM (DDR). Cache line(s) for destination buffer address range is invalidated to ensure that the CPU reads the latest data from the RAM (DDR).

## Downloading and Building the Application

To clone or download this application from Github, go to the main page of this repository and then click Clone button to clone this repository or download as zip file. This content can also be downloaded using content manager by following these instructions.

Path of the application within the repository is apps/xdmac/xdmac_memory_transfer.

To build the application, refer to the following table and open the project using its IDE.

Project Name | Description
--- | ---
sam_a7d65_curiosity.X | MPLABX project for SAMA7D65 Curiosity Board
sam_a7d65_curiosity_pro.X | MPLABX project for SAMA7D65 Curiosity Pro Board

## Setting Up AT91Bootstrap Loader

To load the application binary onto the target device, we need to use at91bootstrap loader. Refer to the at91bootstrap loader documentation for details on how to configure, build and run bootstrap loader project and use it to bootstrap the application binaries.

## Setting Up the Hardware

The following table shows the target hardware for the application projects.

Project Name | Description
--- | ---
sam_a7d65_curiosity.X | SAMA7D65 Curiosity Board
sam_a7d65_curiosity_pro.X | SAMA7D65 Curiosity Pro Board

### Setting Up SAMA7D65 Curiosity Board

Setting up the board:

- Connect the USBA port J3 on the board to the computer using a Type-C USB cable (to power the board)
- Connect the UART Debug port (J35) on the board to the computer using a FTDI-USB cable

### Setting Up SAMA7D65 Curiosity Pro Board

Setting up the board:

- Connect the USBA port J1 on the board to the computer using a Type-C USB cable (to power the board)
- Connect the UART Debug port (J63) on the board to the computer using a FTDI-USB cable

## Running the Application

1. Build the application using its IDE.
2. Open the Terminal application (Ex.: Tera term) on the computer.
3. Connect to the Virtual COM port and configure the serial settings as follows:
   - Baud: 115200
   - Data: 8 Bits
   - Parity: None
   - Stop: 1 Bit
   - Flow Control: None
4. See the following message in the console.

Rev: C