Realtime (Periodic) Input from Slow AI ports

Applications, development tools, FPGA, C, WEB
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Salto
Posts: 3
Joined: Thu Apr 14, 2016 9:52 am

Realtime (Periodic) Input from Slow AI ports

Post by Salto » Sat Jun 04, 2016 11:46 am

I'm now looking for way to use this board as ADC board.
I'd like to use synchronized 4 analog inputs at the rate of 100 kHz.
The spec of this says slow AI works up to 100kHz, however, there are no setting for this rate.
How can I ensure the sampling rate of the slow AI?

I saw some examples of rate setting for IN1 and IN2 as ACQ, but not for slow AIs.
Also checked SCPI command list, but there are no setting command for slow AI sampling rate.
http://archives.redpitaya.com/devel/SCP ... elease.pdf

Nils Roos
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Location: Königswinter

Re: Realtime (Periodic) Input from Slow AI ports

Post by Nils Roos » Sat Jun 04, 2016 2:23 pm

The 4 channels of the slow ADC are set to work at a fixed rate of 100kHz each, there is no configuration option to change it.

It is a bit difficult to actually read the samples at the correct rate, as they are not buffered. If you don't read a sample before a new one is acquired, it's gone. If you read too fast, you'll get the same sample twice (or more).

Salto
Posts: 3
Joined: Thu Apr 14, 2016 9:52 am

Re: Realtime (Periodic) Input from Slow AI ports

Post by Salto » Sat Jun 04, 2016 4:58 pm

Thank you for helpful information.
I understand the point.
So if I want to read it correctly (meaning, no loss and no duplicate), what would be options besides polling it at correct rate?
Is there any interruption for it or some method to make buffer?

nowksru
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Joined: Tue Mar 09, 2021 12:05 pm

Re: Realtime (Periodic) Input from Slow AI ports

Post by nowksru » Wed Apr 21, 2021 3:50 pm

Digging out this thread, because I'm also interested in the answer how to make use of the slow ADCs. I saw the Interrupt output from XADC is connected to the PS (v0.94 Project), so maybe there is a way to see if a new sample is ready? I didn't find the purpose of this connection in the documentation nor the files.

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cheers
Urs

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redpitaya
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Re: Realtime (Periodic) Input from Slow AI ports

Post by redpitaya » Fri Apr 23, 2021 12:15 pm

Please note that the slow inputs initial idea was that it is used for monitoring and not for data acquisition, rather for monitoring.
The data is slower and multiplexed by FPGA, it doesn't have buffer functionality or for example triggering.

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