DAC_DMA_EXAMPLE is a standard example, provided in all no-OS projects, that sends a sinewave on Tx channels using DMA from a lookup table. If you physically loopback a Tx channel to an Rx channel via an electrical wire, you may run the DAC_DMA_EXAMPLE and read the received data at a predefined DDR memory address. You may retrieve the data on the computer for processing/plotting either graphically by using the memory viewer of the SDK or via command line using tickle scripts.
To build the DAC_DMA_EXAMPLE demo, edit the Makefile and add -DDAC_DMA_EXAMPLE to CFLAGS and rebuild. Alternatively, you may simply add a #define DAC_DMA_EXAMPLE in-code and rebuild.