Real-time DSP with red pitaya

[npiro]

Hi! I have a general question about RP.

I would like to perform real-time digital signal processing, e.g. implement a digital filter in the FPGA such that a signal is digitized by the ADC, processed in real time with some math operations, etc, and converted to an output analog signal with the DAC.

I am wondering whether such functionalities are already built in into the API or whether I would have to program new FPGA blocks for this. For instance, how would I do this with the Visual Programming interface?

Thanks a lot!

[Nils Roos]

Hi,
generally, it is possible to implement additional signal processing steps in the signal path within the FPGA and route the processed stream directly to the DAC. The only limits in this approach are available computing resources.

I am wondering whether such functionalities are already built in into the API or whether I would have to program new FPGA blocks for this. For instance, how would I do this with the Visual Programming interface?

The API and the visual programming interface can only work with the already existing logic. They have no mechanisms to reprogram the FPGA, and offer only high-level access to a fixed set of registers.

[npiro]

What is the available logic you refer to? If I find a block in the visual programming interface that does, say, a square root operation, does this mean that this operation is already implemented in the FPGA?
Also, if I want to input a signal from the fast ADC, what pin number do I have to use in the AnalogReadVoltage() function?

[npiro]

generally, it is possible to implement additional signal processing steps in the signal path within the FPGA and route the processed stream directly to the DAC. The only limits in this approach are available computing resources

: Can you point me to some documentation on how to do this?

Thanks

[Nils Roos]

I am not familiar with the Visual Programming module at all, but I am pretty sure that the calculating blocks you use there will not be run in FPGA logic. I expect they will be processed either on the Red Pitaya's CPU or clientside. As I said, there is no infrastructure on the Red Pitaya to create FPGA logic on-the-fly.

What is the available logic you refer to?

The FPGA has memory, arithmetic blocks, registers, and logic gates with which to create DSP functions. If you are not experienced with creating logic designs, there are tools which can aid in the process - up to a point, manually integrating it with the existing Red Pitaya design is still required.
As for documentation, the Vivado suite of applications (which you would be using to do the work) comes with an extensive set of tutorials and guides and has a free version.

Also, if I want to input a signal from the fast ADC, what pin number do I have to use in the AnalogReadVoltage() function?

Maybe somebody with some Visual Programming experience wants to answer this ?