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I'm working on an echo implementation on the board adsp 21262. I've added a buffer to have more samples to work with. I end up then with 4 buffers of size 2048 each.

The problem is that I need to access at least 7000 samples back. (An echo can only be heard with a delay of 1/15th of a second, we have 2*48K~100k samples per second. So we need 100k/15~7k samples).

The problem is that 2048 samples per buffer is the max we can have because afterwards we're out of memory. I'm trying to access the ROM but I have no idea as to how to do that. I've spent a lot of time looking for this information finds nothing.

Thank you !

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closed as unclear what you're asking by A_A, MBaz, Matt L., lennon310, Stanley Pawlukiewicz Dec 21 '18 at 20:54

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • $\begingroup$ Do you think you could rephrase the question for clarity? The first paragraph makes it sound as if you already have acquired 4*2048=8192 samples. The second paragraph states that you need to go back 7000 samples (<8192) and the third states that the problem is that you can only acquire 1 buffer of 2048. Why are you trying to access the ROM? The ROM would be for things like static buffers (for example), you would not be able to write real-time data there (?). $\endgroup$ – A_A Dec 17 '18 at 10:52
  • $\begingroup$ Basically you can only make operations on 2 buffers, and since the buffers get $\endgroup$ – Courtney Dec 18 '18 at 13:53
  • $\begingroup$ We can only make operations on 2 buffers at a time (I think one of the buffers is used by the DAC and the other by the ADC do only 2 usable). So only 2 buffers of size 2048 each let's call them A and B. Output=A[i]+0.5*B[i]. B[i] and A[i] have a 2048 samples delay so I only have 2048 instead of 7000. $\endgroup$ – Courtney Dec 18 '18 at 13:57
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Assuming you have this board, there are 512kByte of SRAM on the board. That should easily accommodate a 7k delay buffer.

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  • $\begingroup$ Thank you I'll look into that. I was looking for ROM answers while I should have been looking for SRAM. It should be easier now to solve my problem. $\endgroup$ – Courtney Dec 18 '18 at 14:00

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