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Review: Hantek DDS 3X25. Anyone own one?
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marmad:

--- Quote ---Great! Welcome to the club.  Please give us feedback also on the buying process and what the package was like when you finally received it.  Enjoy.
--- End quote ---

Thanks!  I bought it on eBay last night from testinstru - notified today that it had been shipped already.

I would LOVE mine to come with an external ROM for the Spartan3AN so that I could pull the firmware out and play with it - but I'm not too optimistic  ;)  But I'll certainly get the logic analyzer connected to the pins of it and the DAC to see exactly what the timing is like between the various pins - and how they are used - for example, the 18 pins used for the multiprocessor link - when each call is made to the DLL.
saturation:
I just perused eBay and now there are a more vendors today that have them for sale, even one USA seller, rikoinstruments.  If the unit isn't off production we have a chance of writing them to release some documentation in exchange for improving their software, as Velleman has done.  It should benefit their sales, so there is incentive for them to cooperate.


--- Quote from: marmad on July 11, 2011, 04:44:35 pm ---Thanks!  I bought it on eBay last night from testinstru - notified today that it had been shipped already.

I would LOVE mine to come with an external ROM for the Spartan3AN so that I could pull the firmware out and play with it - but I'm not too optimistic  ;)  But I'll certainly get the logic analyzer connected to the pins of it and the DAC to see exactly what the timing is like between the various pins - and how they are used - for example, the 18 pins used for the multiprocessor link - when each call is made to the DLL.


--- End quote ---
marmad:
I received my DDS3X25 today.  All seems to work fine - and as previously described here.  I looked inside - same v1.4 PCB and same chips wiped with the exception of the USB controller - which, as Tinhead pointed out in a previous message, was a STM32F103Cx.  What's funny is that they wiped the DC-to-DC converter markings instead - so I think their mind was wandering for a moment ;)

Since the Sync Out is problematic, I wanted to compare it versus Digital Output 11 - which (in generator mode) is the high-order bit of the Waveform Pattern.

First image is a direct comparison - Channel 1 = Sync Out / Channel 2 = DO11

Second image shows DO11 superimposed on a 1MHz triangle wave output from the DDS3X25.  Notice that it changes state at zero crossings of the output waveform, unlike the Sync Out.  That means by putting a jumper between DO11 and any of the Digital Inputs (0-5), it might be possible to write sweep software which changes frequency only at zero crossings - avoiding much of the glitching that might happen otherwise.

Third (Sync Out) and fourth (DO11) images show a single shot 1MHz sine wave triggering a single sweep of the scope.  Sync Out does not appear to respond correctly, but D011 does - and, the period is 1/2 that of the output waveform.

Fifth image shows a 75MHz sine wave along with the DO11 output.  Unlike Sync Out, there is no glitching or out of step problem.

Note - all of the measurements were made with the following setup:
Waveform Output and Sync Out through BNC cable terminated with 50 ohms at scope.
DO11 Output through a ribbon cable (no shielding), then alligator-clipped to a BNC cable terminated with 50 ohms at scope.

When I find some more time, I will get inside with a logic analyzer - and try to glean some better information about what the firmware is doing with various control lines.
Mechatrommer:
dude!
1) save as png or jpg. those bmp's can easily waste half a meg on dave's server. and bandwidth of thousands others.
2) enable frequency counter on your scope so i dont have to take out my calculator
3) retry at odd frequency, like 3MHz, 33MHz, 74.7MHz. 1MHz and 75MHz are known to be "Synch Out" stable
4) How do you manage to output single pulse? teach me the code!
5) How do you manage to sweep at zero crossing by shorting D11 to input? pls explain in detail start from PC App down to signal generation.
6) By right D11 is just least significant digital value of what we see analogically in "Output", so by right it should follow (in synch) with "Output" at any freq, as said, retry (3)
7) Dont quite understand whats the blue trace on pic #3 and #4.
8} Thanks for the report. Hope to hear again.
9) Cheers ;)
saturation:
Great job marmad, a lot to digest, so more later.  Was your purchase experience without a problem? I presume so as you didn't mention it and you went straight into putting it to work  ;D .
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