This example application shows how to continuously transmit and receive data over a SPI
interface using ping pong buffers with the DMA.
Parent topic:Harmony 3 Peripheral Library Application Examples for SAMA5D2 Family
DMA peripheral provides support to implement ping-pong buffering. DMA transmits and
receives data from one pair of buffers, when CPU works on the second pair.
When DMA is transmitting data from ping buffer, CPU works on pong buffer. When DMA
completes transfer, it generates an interrupt to indicate transfer completion from
ping buffer. DMA channel is automatically re-initialized to transmit data from pong
buffer while the CPU works on the ping buffer.
When DMA is receiving data to ping buffer, CPU works on pong buffer. When DMA
completes transfer, it generates an interrupt to indicate the availability of data
in the ping buffer. DMA channel is automatically re-initialized to receive data in
the pong buffer while the CPU works on the ping buffer.
Data is transmitted and received in loopback mode by shorting the MISO and MOSI
lines. At the end of transfer, received data is compared with transmitted data to
confirm data match.
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/spi_ping_pong_with_dma/firmware.
To build the application, refer to the following table and open the project using its
IDE.
Project Name | Description |
---|---|
sam_a5d2_curiosity.X | MPLABX project for SAMA5D29 Curiosity Development Board Kit |
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.
The following table shows the target hardware for the application projects.
Project Name | Description |
---|---|
sam_a5d2_curiosity.X | SAMA5D29 Curiosity Development Board Kit |
SETTING UP THE BOARD
Refer to the following table for LED name:
Board | LED Name |
---|---|
SAMA5D29 Curiosity Development Board | RGB_LED (Green) |
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