PC Oscilloscope ... getting better

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