Author Topic: Digital oscilloscope without FPGA  (Read 9367 times)

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Offline NiHaoMike

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Re: Digital oscilloscope without FPGA
« Reply #25 on: August 07, 2017, 03:31:50 pm »
Beaglebone Black can do it, but 100MSps is a pretty slow scope.
https://github.com/abhishek-kakkar/BeagleLogic
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Online David Hess

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Re: Digital oscilloscope without FPGA
« Reply #26 on: August 07, 2017, 04:01:59 pm »
Beaglebone Black can do it, but 100MSps is a pretty slow scope.
https://github.com/abhishek-kakkar/BeagleLogic

That is a modern example of the DMA method using integrated memory.  The ARM processor in the BeagleBone includes a pair of 200 MHz 32 bit PRUs (PRUSS = Programmable Realtime Unit SubSystem) which can be programmed to operate effectively as a DMA controller or many other things:

http://processors.wiki.ti.com/index.php/Programmable_Realtime_Unit_Subsystem

That kind of processor seems ideal for something like a FPGA-less DSO although it would be limited to parallel interface ADCs.  That is not a problem though because existing parallel interface ADCs can operate at 100 MS/s and faster.  Some of them have bandwidths of 1 GHz and above (LTC2242 and at 12 bits!) so you could make quite a useful DSO although it would have to support equivalent time sampling to take advantage of that kind of bandwidth.

Supporting more than one input channel might be a problem but the processors are cheap (and the ADCs are not) so use one per ADC.
 

Offline nctnico

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Re: Digital oscilloscope without FPGA
« Reply #27 on: August 10, 2017, 08:33:58 pm »
All very interesting information!

The raspberry pi was just an example.
The question is if a FPGA is always needed.
Are their any other systems/cpu that can handle the amount of data.

But as far as I understand the answers, the answer is no   ;)
A videochip with hundreds of processor cores has lots of bandwidth to deal with data. If you could glue a fast ADC onto a (multi lane) PCI express bus you can probably get quite far. Unfortunately that glue part is likely an FPGA.
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