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PC Oscilloscope ... getting better

Started by Francesco Poderico March 31, 2013
On 3/31/2013 4:52 PM, Francesco Poderico wrote:
> Hi all, > a few months ago I started to design and build my own oscilloscope...and in this groups I had a lot of help in solving some problem... > > http://thefpproject01.blogspot.co.uk/ > > I'm getting so excited now... and surprise at same time... how things are getting better and better. > The oscilloscope is now very useful indeed, I have added the capability to see the spectrum, and it works really well. > > I still have a long way to go... but it looks promising. please see the picture on my blog. > > I'm starting thinking at the next prototype now... > shall I go for a 200 MHz + 64 KRAM ( which I can put on the market for less that 200 pounds cheap oscilloscope but does what it says...) or shall I prototype a 1GSPS? and have a larger margin? > Any suggestions is welcome.
You seem to be doing good work. Is your spec of 5 mV/div really valid? That would be pretty nice. Most of the low cost scopes don't do so well on sensitivity. -- Rick
On Sun, 31 Mar 2013 13:52:24 -0700 (PDT), Francesco Poderico
<francescopoderico@googlemail.com> wrote:

>Hi all, >a few months ago I started to design and build my own oscilloscope...and=
in this groups I had a lot of help in solving some problem...
> >http://thefpproject01.blogspot.co.uk/ > >I'm getting so excited now... and surprise at same time... how things =
are getting better and better.
>The oscilloscope is now very useful indeed, I have added the capability =
to see the spectrum, and it works really well.
> >I still have a long way to go... but it looks promising. please see the =
picture on my blog.
> >I'm starting thinking at the next prototype now... >shall I go for a 200 MHz + 64 KRAM ( which I can put on the market for =
less that 200 pounds cheap oscilloscope but does what it says...) or = shall I prototype a 1GSPS? and have a larger margin?
>Any suggestions is welcome. > >Thanks, >Francesco
Maybe 500Ms/s and 1 Ms ram. Really long record lengths have some = specific usefulness. ?-)
On 4/5/2013 2:07 AM, josephkk wrote:
> On Sun, 31 Mar 2013 13:52:24 -0700 (PDT), Francesco Poderico > <francescopoderico@googlemail.com> wrote: > >> Hi all, >> a few months ago I started to design and build my own oscilloscope...and in this groups I had a lot of help in solving some problem... >> >> http://thefpproject01.blogspot.co.uk/ >> >> I'm getting so excited now... and surprise at same time... how things are getting better and better. >> The oscilloscope is now very useful indeed, I have added the capability to see the spectrum, and it works really well. >> >> I still have a long way to go... but it looks promising. please see the picture on my blog. >> >> I'm starting thinking at the next prototype now... >> shall I go for a 200 MHz + 64 KRAM ( which I can put on the market for less that 200 pounds cheap oscilloscope but does what it says...) or shall I prototype a 1GSPS? and have a larger margin? >> Any suggestions is welcome. >> >> Thanks, >> Francesco > > Maybe 500Ms/s and 1 Ms ram. Really long record lengths have some specific > usefulness.
Can you even buy 64 kword RAMs these days? A 32 MB SDRAM chip will do all that is needed I believe. Either run it at 100 MHz with twice the width of the storage needed or I expect it won't be hard to find SDRAM that can be clocked at 200 MHz. This wouldn't add much to the cost of the device, but would greatly improve functionality. -- Rick
On Fri, 05 Apr 2013 20:22:49 -0400, rickman <gnuarm@gmail.com> wrote:

>On 4/5/2013 2:07 AM, josephkk wrote: >> On Sun, 31 Mar 2013 13:52:24 -0700 (PDT), Francesco Poderico >> <francescopoderico@googlemail.com> wrote: >> >>> Hi all, >>> a few months ago I started to design and build my own =
oscilloscope...and in this groups I had a lot of help in solving some = problem...
>>> >>> http://thefpproject01.blogspot.co.uk/ >>> >>> I'm getting so excited now... and surprise at same time... how things=
are getting better and better.
>>> The oscilloscope is now very useful indeed, I have added the =
capability to see the spectrum, and it works really well.
>>> >>> I still have a long way to go... but it looks promising. please see =
the picture on my blog.
>>> >>> I'm starting thinking at the next prototype now... >>> shall I go for a 200 MHz + 64 KRAM ( which I can put on the market =
for less that 200 pounds cheap oscilloscope but does what it says...) or = shall I prototype a 1GSPS? and have a larger margin?
>>> Any suggestions is welcome. >>> >>> Thanks, >>> Francesco >> >> Maybe 500Ms/s and 1 Ms ram. Really long record lengths have some =
specific
>> usefulness. > >Can you even buy 64 kword RAMs these days? A 32 MB SDRAM chip will do=20 >all that is needed I believe. Either run it at 100 MHz with twice the=20 >width of the storage needed or I expect it won't be hard to find SDRAM=20 >that can be clocked at 200 MHz. This wouldn't add much to the cost of=20 >the device, but would greatly improve functionality.
The 64k is a ram block inside the FPGA. Completely different situation. ?-)
On 4/5/2013 10:12 PM, josephkk wrote:
> On Fri, 05 Apr 2013 20:22:49 -0400, rickman<gnuarm@gmail.com> wrote: > >> On 4/5/2013 2:07 AM, josephkk wrote: >>> On Sun, 31 Mar 2013 13:52:24 -0700 (PDT), Francesco Poderico >>>> >>>> I'm starting thinking at the next prototype now... >>>> shall I go for a 200 MHz + 64 KRAM ( which I can put on the market for less that 200 pounds cheap oscilloscope but does what it says...) or shall I prototype a 1GSPS? and have a larger margin? >>>> Any suggestions is welcome. >>>> >>>> Thanks, >>>> Francesco >>> >>> Maybe 500Ms/s and 1 Ms ram. Really long record lengths have some specific >>> usefulness. >> >> Can you even buy 64 kword RAMs these days? A 32 MB SDRAM chip will do >> all that is needed I believe. Either run it at 100 MHz with twice the >> width of the storage needed or I expect it won't be hard to find SDRAM >> that can be clocked at 200 MHz. This wouldn't add much to the cost of >> the device, but would greatly improve functionality. > > The 64k is a ram block inside the FPGA. Completely different situation.
Of course... I'm used to using the poor stepchild end of the FPGA families with only a few kB of RAM. Still, I think a RAM chip should be on the board. It seems silly to hobble what seems to be a good design. I know the extra storage would help the work I do. I think I've offered my help before, but I'll make the same offer. I have some experience with memory interfaces. -- Rick