Products > Test Equipment

SainSmart DDS120 & DDS140 USB Oscilloscope

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psynapse:
Wow donut6, you're a dark horse!

If yours is a ground up re-write, yes I would be very interested in seeing it.  It would be great to avoid any accusation of plagerism by this group (well by me actually ;-)).  I do not feel comfortable posting my annotated disassembly in open forum (at least until I understand the legal situation), and equally I could well understand if you want to keep your code "pure"  .... I could flag where anomomies lie if that would help.  Does anybody understand the legal position with regard to dissassembled code?

Edit:

Just did a little search

"Now, publishing results of disassembly on blog, that's another thing ...... under European law you can do reverse-engineering, but you may not publish the results. Publishing your source code, that you've created thanks to what you found out, should be completely OK."   Not written by a lawyer of course!  But a useful indication nevertheless.

And also (in the US)

".... Accolade’s “intermediate” copying (i.e., copying solely in order to discover functional interface specifications that were then independently implemented) was a fair use, emphasizing that disassembly was the only way to gain access to the ideas and functional elements .... "

So I guess keeping your code pure is a good idea for all of us.  Would still love to see what you have done though.  My plans were to add two key functions into the firmware.

1) Add an additional command to set a "go code" pending flag.  Then add an ISR for interrupt 5, which would (if the flag permits) issue a go code.  This would provide an external trigger (int5 pin wired to the external socket, preferably through a buffer).  The only trouble would be that data acqusition would start 2 -5 microseconds after the trigger .
2) Add an additional command to write 2 bytes into the RAM copy of the "alternate" wave table used just for mode 0A.  Writing these two bytes will change the sampling rate generated by the GPIB.  I have already verified that this works by patching the two bytes manually.

What method are you using to upload your firmware?  Writing the EEPROM is OK, but leaving the link open and using cycfx2prog to do a direct ram load is much easier ..... but I am guessing you know that!

Great work.  If we could get away from the provided firmware altogether, that would be fantastic.  As Ganzuul noted some time ago , it would be nice to know what that CPLD does,  still something on my to do list. Given that, I am pretty certain we can do a better job than SainSmart

psynapse:
mmark,

I have just added command 94 0A to my scope software (for the DDS140), that is the 240khz mode that perhaps copies the DDS120 mode of working  ....... and when I start a fresh scan I get 4096 bytes of "old" data at the beginning ...... indicative of poor fifo flushing.  I have tried using codes D0,D1 (which I think are fifo reset and set) and this blows up the scope nicely ... hard reset needed.  So I am guessing that the DDS140 has a similar problem to that you are finding on the 120 . I will look again at the fifo reset firmware.

In the meantime perhaps just ditch the first 2^n bytes, because I at least always get that result

EDIT:  Blast!  I have also seen 3072, more and more like and endpoint buffer issue

doctormord:
Great discussion.  Here in Germany disassembling someones code is prohibited by law (this also belongs to reverse engineering) AFAIK.

But i would first think about the complexity of the problem and what's the initial intention is to hack something.

I mean, the DDS120 is mainly an FX2LP dev board with some analog circuit.. Nothing special in general.

The firmware, buggy
The software, buggy
The hardware, buggy
...
Linux? Nope!

Claimed to be open source and maker community friendly? Yes..

So, to my understanding, what we are doing here, is, to make things work like intended. :))

There can't be much magic in the actual official firmware that isn't covered by the technical references. (I guess)

So, would say, keep it coming.

To be free, an open source firmware, compatible with the official one would be nice. (Advanced and with new magic)

Regards.

Christian

Edit:

@psynapse

I can't extract your scope2.zip (Windows & Linux)

jimon:
Btw, I've ordered FX2LP dev board recently (should arrive in 1-2 weeks), should I try just to hijack ADC-FX2 traces ? probably it should be simple enough mod.

PS. Will order FX3 board if FX2 board will be successful, but I have a little knowledge what to do with GPIF II

doctormord:
Let's go! O0

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