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SainSmart DDS120 & DDS140 USB Oscilloscope

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psynapse:
Doctormord,

Thanks!  I am not sure I know what you mean by pre-buffer though .... could you explain please .... could be a neat idea.

What I would have liked was a constantly running cyclic buffer, which you stop shortly after the transient of interest.  That is possible (through PC software) on the both the DDS120 and the DDS140 94(0A) mode, but not for the flash capture mode that runs at 10 and '100' Mhz on the 140.  Ganzuul, I really must get round to listening to the CPLD JTAG to see if it can be reprogrammed to do that.   I note that the CPLD continues to strobe the !WE pin on the memory after the buffer is full (right until the host issues command 50), but I have not yet checked to see if it has enabled !CE or cycles address pins ... I think not.

For me, I can arrange that external events that I wish to monitor can be triggered by a ready signal from the scope.  And I know / think that continuous data logging will be possible to 12Mhz (perhaps 24Mhz) , which meets my needs (and perhaps Doctormords).  And with a hardware input trigger that will fire data acquisition within 1-2uS it is as far as I need to go for my needs.  Doctormord has a fix to up the data-rate on the ADC side of the DDDS120.  So......

What is left to do?????

.......The PC software needs tidying up and it would be really nice to have open firmware

But nearly everybody has gone quiet.  That could be a loss of interest or that everybody is busy elsewhere, or that folk are hard at work on recrafting code.

Which is it folks?

CatWhisker:
Psynapse,

Stumbled on this yesterday, I'll definitely be interested.

What 'scope software are you targetting? Or going a-fresh?

doctormord:
Psynapse,

i meant preroll with hw-trigger, didn't knowed that you meaned flash-capture.

Up to 50msps it should work with realtime pass through into the PC. The other way I could think of is live data at reduced speed with additional (triggered ) flash capture into the clpd fifo - so having a big set if reduced resolution data with additional highres (magnification) added from flash capture.

psynapse:
Doctormord

Yes, pre  -roll will work well, although it might be nice to have an external signal "mark" the start of the region of interest.

And yes on the CPLD too   ... I need to come to grips with that.  However I have learned so much from this exercise, and our valuable conversations, that my inclination is to build a new scope from scratch, especially since this thread seems to be going cold (a real shame).  I now have a MAX1446 ADC and an FX2 development board,  the challenge for me now is making a PCB for it all to happen on!  I was thinking of a true FIFO chip to get transient data rates up and allow continuous data acquisition up to 48M.  If I find the time and energy, I will certainly be implementing the front end revisions you have identified, for which many thanks.

CatWhisker

What we are trying to achieve here is both open software and firmware (along with some significant hardware improvements).  We are a long way forward on open software for both the Windows and Linux environments (there is still a lot of tidying up to do, but proof of principal we definitely have).  We are less far forward on open firmware for the scope itself.  I have "contaminated" myself by looking at a disassembly of part of the provided code, which makes it very difficult for me to claim that I have invented my firmware from scratch.  However I do know how to patch the standard code to give us extra features.  If we do not get open firmware, I will look carefully at the legality of releasing details of how to zap the firmware in order to give extra functions. 

doctormord:
Preroll with external mark, yes, that's what I thought off.

Would you implement the stuff for the DDS120 into your software as well? Thanks.

If I find some spare-time, I'll redraw the AFE (started already) and think about the wiring for interleaving the channels.

Regards,

Doc

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