[chbot] DigitalDiscovery

Charles Manning cdhmanning at gmail.com
Thu Jan 18 22:40:28 GMT 2018


There are various trigger options.

One thing that I wanted to do, but could not, was use an external pin as a
sample clock to capture 20MHz clocked parallel data.

Instead I ended up sampling the data + the clock line at 50MHz then using
software to recover the clock edges and the parallel data. Simple enough,
but it reduced the depth of data I could capture.



On Fri, Jan 19, 2018 at 10:58 AM, Mike Field <hamster at snap.net.nz> wrote:

> I suspect the desred solution is to generate a trigger pulse from the
> pattern generator, and use that to trigger the logic analyzer. It has
> plenty of channels to allow that.
>
> However, you can also do it another way, bysetting up triggers that start
> pattern generator.
>
> Mike
>
> -------- Original Message --------
> Subject: Re: [chbot] DigitalDiscovery
> From: Charles Manning
> To: Christchurch Robotics
> CC:
>
>
> Please explain what you mean by "synchronous capture and generation".
>
>
>
> On Thu, Jan 18, 2018 at 7:23 PM, Mark Atherton <markaren1 at xtra.co.nz>
> wrote:
>
>> Charles,
>>
>> does this unit do synchronous capture and generation ?
>>
>> -M
>>
>> On 18/01/2018 5:50 PM, Charles Manning wrote:
>>
>>> Even if it works under Wine, it will likely have issues due to not being
>>> able to transfer at full USB speeds.
>>>
>>> The Saleae kit is good. Anyone who rips them off is scummy IMHO.
>>>
>>> I have an old Salaea (8 chan/24Msps) and have recently bought a
>>> DigitalDiscovery from Digilent because I needed some more channels and more
>>> speed (I needed up to 100MHz, but this goes up to 800MHz).
>>> It can also generate waveforms.
>>>
>>> https://store.digilentinc.com/digital-discovery-portable-log
>>> ic-analyzer-and-digital-pattern-generator/
>>>
>>> It also works under Linux. Not nearly as pretty as Saleae, but did the
>>> job.
>>>
>>> It stores samples in the onboard 2Gbit DDR which limits the sample depth
>>> to a 64Msamples or so.
>>>
>>> What is really neat about the DigitalDiscovery is that it comes with a
>>> C/C++ + Python API that allows you to program up "test scripts" etc.
>>>
>>> For example, I needed to capture data into files then run some FFTs etc.
>>> All very easy, scripted and allowed me to re-run tests etc without messing
>>> about clicking the UI hundreds of times.
>>>
>>
>>
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>
>
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