dual mode AD2+AD3 potential implementation

[Anthocyanina]

So, having an AD2, the AD3 doesn't look like a significant enough upgrade on its own, and having an AD2, buying an AD3 would mean still having basically the same functionality as a single AD2 with minor improvements. I'm wondering about the likelyhood of implementing dual mode for an AD2+AD3, making the AD3, the slightly more capable instrument, run in what would be an AD2 mode of sorts. limiting its capabilities to match those of the AD2 while running both together to form a 4 channel instrument, and then when using it alone, being able to run it as it normally would. I think having this option would make it easier to justify the purchase of an AD3, as now it would not only bring the minor improvements over the AD2, but also, in a way, expand the capabilities of both test instruments by being able to run them in dual mode.

Because using the AD3 as a replacement for the AD2, when you already have an AD2, it doesn't make a lot of sense for the cost when that would mean one of the instruments would go live in a drawer or be sold, or be kept as backup or something, but wouldn't be of use at the same time.

So, how likely is it for a combined dual mode to be implemented?

Thanks!

[JColvin]

Hi @Anthocyanina,

Digilent will be updating (edit: did update) the blog post with some additional information that I typed up regarding the possibility of mix and matching devices. What I had recommended to be added is the following:

Quote

August 29th, 2023 update from Digilent Staff: 

This Dual Mode post focused on pairing two identical devices to be able to use them simultaneously within a single instance of WaveForms, but did not address the question of if different devices can be mixed and matched through Dual Mode, such as the Analog Discovery 3 paired with an Analog Discovery 2.

Mixing and matching devices is not supported within the WaveForms application, although it can be easily done through WaveForms SDK using existing examples such as Device_Synchronization.py.

Additionally, Dual Mode within the WaveForms application is best supported and used by devices that can use an external reference clock such as the Analog Discovery 3 or the Analog Discovery Pro 3000 series boards. Devices that do not have an external reference clock, such as the Analog Discovery 2 or the Eclypse Z7, while still supported by Dual Mode when a pair of a singular device is used, will eventually have the samples between the two devices shift over time due to differences in jitter between the independent oscillators on each device.

The Digital Discovery do not have dedicated Trigger I/O pins nor a reference clock, so Dual Mode is not supported. However, recent versions of the WaveForms software have added 40-bit Logic Analyzer Support for a single Digital Discovery.

Some additional information about Dual Mode is available from the WaveForms developer on the Forum here: https://forum.digilent.com/topic/25957-digital-discovery-portable-usb-logic-analyzer-and-digital-pattern-generator/, and the latest version of the WaveForms software that adds support for the 40-bit capture for the Digital Discovery is freely available on the Digilent Forum here: https://forum.digilent.com/topic/8908-waveforms-beta-download/.

 

As for JColvin's personal, yet slightly vague, perspective on the (since I don't have budgetary or decision making powers in any sense) the AD3 with AD2 or double AD2 combo for Dual Mode to help add value / make it so the AD2 is not forced to live forgotten on a shelf collecting dust. I think this could be a useful addition to have, but this comes with a couple caveats that I'll reiterate below.

- AD2 does not support an external clock input (whether solely due to the FPGA logic being full, the Spartan 6 architecture not allowing it in the same way, lack of dedicated PLL that accepts external clocks, some or all of the above, I do not have insight on). Regardless, this ultimately means that while you can pass the trigger signal between two AD2's, because the Analog Discovery 2, whether paired with a second AD2 or a different T&M device, will be working on its own independent oscillator with its own jitter, so you will experience drift on the samples between it and whatever other device. You can potentially mitigate this by stopping and restarting both devices periodically, but that doesn't actually resolve the problem.

- This is a bit more esoteric, but there's also the question of how much additional combinations should be supported natively within the application; the more combinations, the larger the installation size for a feature that fewer and fewer people will be able to take advantage of. I personally think there is a big enough market segment for an AD3 & AD2 combo, but I don't know where that metaphorical line in the sand might be. Plus you can (and have always been able to, at least as far as I know) be able to synchronize different devices to have them collect data together through WaveForms SDK but this is of course a software timed solution.

So in an unhelpful conclusion, is AD3 & AD2 Dual Mode available? No, but technically yes, but no it's not available in the GUI. Will that change? I do not know.

Thanks,
JColvin

[Anthocyanina]

Interesting, thank you, i didn't know about this being possibled through the SDK.

About what you mention regarding the clock. given that the AD3 does support an external clock, or syncing it, it having a larger FPGA, i think would mean it is possible to have the AD3 syncing its clock with the AD2, maybe through the trigger system or a dedicated digital pin on the AD2 generating a clock and it being read to sync to on the AD3?

Knowing different instruments can work together sort of as one using the SDK does change things a bit, but having this supported on the waveforms GUI would be really, really nice, and about device combinations supported natively, I would be biased, of course, saying AD2+AD3 minimum would be enough, but i think this would also be the most likely scenario for most people, and the one which most people interested in dual mode might care about the most, with how popular the AD2 has been over the years, and how useful it still is today.

Thanks again!

A small edit to mention that my question about generating a clock with the AD2 to sync the AD3 is more to learn if that is practically possible with the hardware than it is about how likely it is that that gets implemented that way, although i also want to know about the likelyhood of it happening, if practically achievable, of course. (not so small an edit after all!)

Edited August 30, 2023 by Anthocyanina

[attila]

Hi @Anthocyanina

It would not be impossible to implement dual device support in the WF app for AD2+AD3 but it would rise some complications since the devices have different buffer allocation for different configurations and new features.

 

[Anthocyanina]

hi @attila yes, i understand, that's why i mentioned, since the AD3 has the larger FPGA, larger buffer, and is the better instrument, if it could be set to run in some form of "AD2 mode", by artificially limiting it in software so that it matched the AD2 when running both at the same time, but that it went back to its full capabilities when running it alone, or with another AD3. would this be practially realizable? 

Thanks!

[JColvin]

Hi @Anthocyanina,

Is it realizable? Almost certainly. As a wise Digilent employee has told me on more than one occasion, "it's just typing".

Is it practical? That's a question that I'm not able to give an answer to. My opinion is yes this should be considered, but either option of creating a pseudo reduced mode for the AD3 or changing the architecture of the AD2 so that one of the digital pins is completely isolated from the rest of the design so that it can output a stable clock to another device is not a trivial amount of work (particularly the second option).

I do know that the more customer interest there is in a particular feature, the more likely it will be implemented. I know there was a decent amount of interest and multiple questions about this feature after the blog post on Dual Mode was called out in the newsletter (or at least I presume that's what prompted your question to begin with), so Digilent is aware of the customer interest.

But Digilent also needs to have some sort of boundary so we aren't constantly asking Attila to add other new device combinations as Digilent will, of course, continue to make Test and Measurement products so the number of possible combinations will just continue to increase, adding more feature and size to the software that only a small number of users would realistically be able to benefit from. Where this metaphorical line in the sand is, I don't know.

I'll stop musing for now.

Thanks,
JColvin

[Anthocyanina]

hi @JColvin

Thank you! yes, of course, as someone just getting started with FPGA and finding it quite challenging, i understand it would not be trivial. I appreciate the response, and just want to add that, as the response, i really appreciate how Digilent is the only company that listens so closely to the users of their products, and that's something amazing, and for which i'm really thankful. I completely understand not every suggestion can be implemented, and i think it's great that you at least respond, whether something will be implemented or not. That's something no other company in my experience does, and it's one of the reasons i will continue to use and acquire Digilent's products.

Thank you again, really, just getting a response about this is cool, it is, if anything, a glimpse into what goes on behind the developmet of a feature, like what considerations go behind that and all that, and that's cool.

I look forward to future waveforms updates, and your future products. if this eventually becomes part of it, great! if it doesn't, perfectly understandable, and again, thank you, and thank you for engaging so much with the community.

[attila]

Hi @Anthocyanina

I tried to add reference clock output support to AD2, to allow AD2+AD3, but unfortunately the AD2 FPGA is so full that additional logic for such a feature cannot fit.