RP_NOTS Returned by AXI Functions

[matankeda]

Hello,

I am trying to test the AXI mode example for the 4-input Red Pitaya. When compiled the AXI-related functions return RP_NOTS or 24. I am currently using Red Pitaya OS 2.00-18.

Am I doing something wrong, or is the library not finished?

Thank you.

[redpitaya]

Hello matankeda,

We are currently in the testing stage for AXI mode (with the latest Nightly Builds). If you want to try it out. Please follow the instructions found in the "README.txt" for the Nightly Builds (install the latest Linux OS for Red Pitaya (2.01)), but do not install the ecosystem:
- Nightly builds instructions: https://downloads.redpitaya.com/downloa ... ly_builds/
- Linux OS: https://downloads.redpitaya.com/downloads/LinuxOS/

Next, download the AXI test ecosystem from here:
https://downloads.redpitaya.com/tmp/eco.zip

And extract it according to the instructions in the README.txt (in the Nightly Builds section)

The example should be able to acquire 128 MB per channel with the AXI mode.

Should you need additional help, please let me know.

[matankeda]

Hello,

I was able to download the OS and Ecosystem successfully, but when running the AXI example, the code errors and displays this message:

Reserved memory start 0x108CCD size 0x13A000
rp_AcqAxiSetDecimationFactor failed!
tail: cannot open 'out.txt' for reading: No such file or directory

Could you offer any recommendations for troubleshooting and resolving this issue?

Thank you for the quick reply, it is highly appreciated.

[matankeda]

Quick correction,

The AXI functions do work on the 2-input (Z10_125) RP board, but fail to work on the 4-input (Z20_125_4CH) board.

When do you intend to incorporate the AXI features into the 4-input RP?

Thanks again.

[redpitaya]

Sorry for the late reply.

Thank you for reporting the feature not working on the 4 Input boards. I will need to check with the team when we plan to support the AXI feature with the 4-Input version of STEMlab

Just as a side note. When reading from the AXI memory you should consider the addresses returned by the AXI mode as the address of the first sample in the buffer/memory (each sample is 8 bytes long and the address points to the first byte) and the last sample (the last sample stretches from the last address to the last address + 7 bytes).

This should also be taken into account when passing the memory addresses to the function (you have to pass the start of the first sample and the start of the last sample): So if you want the memory to be between addresses 0x100 and 0x200, you need to pass (0x100 and (0x200 - 8)) (address 0x200 will be the first address outside the buffer in this case).

Please let me know whether additional clarification is needed.

[matankeda]

Hi,

Thank you for your response, I am looking forward to any updates!

[redpitaya]

Hello matankeda,

Thank you for your patience.

I consulted with the team. As of now, the 4-Input does not yet support the AXI streaming mode as it has just been developed for a standard STEMlab 125-14, but in the future, we plan on expanding it to the 4-Input as well.

[matankeda]

Hi,

Thanks for the speedy reply, is there an estimation to when the AXI features would be available for the 4-input RP? If so, when?

Lastly, I also measured the speed of the rp_AcqAxiGetDataRaw function and found it to be approximately 10 megabytes per second, which seems rather slow. Is this the expected or appropriate speed for this function?

Thanks again.

[redpitaya]

Hey matankeda,

As of now, we do not have an estimation, but it will come with the next OS update (the version after 2.00-23).

That is the same speed at which the Streaming application can transfer data directly to the computer. I do not know the exact details and the developers are quite busy at the moment. If you want to achieve higher speeds the best would be to modify the source code of the function.
Here is the link to the source code, you are free to modify the functionality according to your wishes:
https://github.com/RedPitaya/RedPitaya/ ... er.c#L1061

Please note that a recompilation of the ecosystem will be required after modification. You can find the details here:
https://redpitaya.readthedocs.io/en/lat ... -ecosystem