DAC streaming configuration

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The DAC configuration section allows the user to set the parameters for the data generation process. The settings depend on the selected Mode (Network or Local).


Configuration modes

The user can set:

The other settings are specified in the configuration file located in /root/.config/redpitaya/apps/streaming/streaming_config.json. The file can be updated manually or through the Command Line Client.

WAV and TDMS file formats can have up to two channel signals at the same time. While Channel select is not available, the first channel will be generated on OUT1 and the second channel on OUT2.

Note

Currently, the only supported format is 16-bit RAW. In the future we will also support other formats and 8-bit mode.


DAC streaming modes

The DAC streaming has two modes of operation:

  • One-pack mode - The data file is smaller than the block size variable. The data is sent to the board only once and generated repetition number of times. This allows for a maximum DAC rate of 125 MS/s.

  • True streaming mode - The data file is larger than block size. The data is streamed from the computer to the board. This allows for a maximum DAC rate of 62.5 MS/s.

One-pack mode

If the data file size is smaller than the block size variable, the application will transfer a single block of data to the board (block_size) from the computer. The generation data is stored in the DMM memory and can be generated at full core clock speed (typically 125 MHz). The data is generated the specified number of times, as set in the Repeat count setting.

  • Maximum dac_rate - Typically 125 MHz (125 MS/s) (depends on the core clock speed of the FPGA)

  • Use case - Short waveforms, arbitrary waveform generation


True streaming mode

If the data file size is larger than the block size variable, then the data is streamed from the computer to the board. To achieve the best performance, we recommend setting the block size to 1 MB or higher.

  • Maximum stable dac_rate - 62.5 MHz (62.5 MS/s)

  • Use case - Long waveforms, continuous signal generation

Warning

Setting the DAC rate higher than 62.5 MHz in true streaming mode may result in gaps in the generated signal and unstable signal generation.

Note

Remote data generation is currently possible only through the Command Line Client. The desktop application currently does not support this feature.


File formats

The following file formats are supported for DAC streaming:

  • WAV (Wave Audio File Format) - Standard audio file format. Maximum file size is 4 GB.

  • TDMS (Technical Data Management Streaming) - National Instruments file format.

Both formats can contain up to two channels (OUT1 and OUT2).

Note

The DAC streaming is currently limited to 16-bit resolution and the WAV or TDMS file format. The WAV file format has a maximum size of 4 GB, which limits the maximum number of samples that can be generated to approximately 268 million samples (for 16-bit resolution).


Data generation limitations

For the practical limits and recommended settings for DAC streaming, see Data Generation Limitations.


Simultaneous ADC and DAC streaming

ADC and DAC streaming can work simultaneously, allowing the user to acquire data from the fast analog inputs and generate signals on the fast analog outputs at the same time.

Note

Please note that the load on the processor will increase and the maximum performance of each mode will decrease when running both modes simultaneously.


Next steps