SPI Self Loopback DMA

This example application shows how to use the SPI peripheral with DMA to transmit and
receive a block of data.

Parent topic:Harmony 3 Peripheral Library Application Examples for SAMA5D2 Family

Description

This example demonstrates transmit and receive operation over SPI interface using
DMA. Two DMA channels are used - one for transmission and another for reception. The
loop back test requires the MOSI output pin to be connected to the MISO input pin so
that anything transmitted will also be received. The example first transmits 10
bytes and receives 10 bytes. If the received data is same as transmitted then it
transmits 0 bytes and receives 10 bytes. In this case, dummy data will be
transmitted to receive 10 characters, hence all the received data should be 0xFF.
Next, 10 bytes are transmitted and 5 bytes are received. Here, the received bytes
must match the first 5 bytes in the transmit buffer. Finally, 5 bytes are
transmitted and 10 bytes are received. In this case, the first 5 bytes in the
receive buffer must match the first 5 bytes in the transmit buffer. The remaining 5
bytes in the receive buffer must be 0xFF.

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/spi/master/spi_self_loopback_dma/firmware.

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

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.

Setting Up SAMA5D29 Curiosity Development Board

SETTING UP THE BOARD

• Short Pin 5 and Pin 6 of mikroBUS1 connector.
• Connect the Debug USB port on the board to the computer using a Type-C USB cable

Running the Application

1. Build the application using its IDE
2. LED indicates the success or failure:
   • The LED is turned ON when the received data matches the transmitted data

Refer to the following table for LED name: