Re: [Minila-forum] Some questions about MiniLA

[Jan S. <jan...@vo...>]

Hi,

   the important properties are:
 - pin compatibility, size, data width (>=32 bits)
 - flowthrough mode support
 - cycle time < 10ns
 - data setup time <= 2ns
 - data hold time <= 2ns

   I did not spend too much time with it but your second option 
MCM69F737TQ7.5 seems to be usable.

   Jan


Myscha napsal(a):
> Hello,
>
> thank you for welcoming me and thanks for the answer.
>
> What SRAM-properties are important? That should mean: which criterias are 
> important when choosing a SRAM?
> I found a number of possible replacements, but I'm not sure, whether they 
> will do or not.
>
> Regards,
> Michael
>
>
> ----- Original Message ----- 
> From: "Jan Smrz" <jan...@vo...>
> To: <min...@li...>
> Sent: Sunday, December 23, 2007 1:01 PM
> Subject: Re: [Minila-forum] Some questions about MiniLA
>
>
>   
>> Hello,
>>
>>   be welcome. Please see answers below:
>>
>> Myscha napsal(a):
>>     
>>> Hello,
>>>
>>> I want to build a MiniLA and I'm searching for the parts therefore.
>>>
>>> Does anyone have parts he doesn't need, especially the PCB (with USB),
>>> the CPLD, the SRAM and the oscillator?
>>>
>>>
>>> And I have some other questions, too:
>>>
>>> 1. Can the XC95288XL be replaced with a XC95144XL? I know this
>>> questions has already been asked, but it was not answered in English.
>>>       
>> Unfortunately not, the XC95144 is too small. I tried to make some
>> limited version of miniLA for this device but  the limitations were so
>> high that no -144 version of firmware was released.
>>     
>>> 2. Is it neccessary to have a pipelined burst SRAM or will one without
>>> pipeline also do?
>>>       
>> The pipeline mode is not used. SRAM runs in flowthrough mode. Some
>> people were having problems obtaining the memory and they successfully
>> tried an alternative - IS64LF12832A-7.
>>     
>>> 3. What is limiting the speed? The CPLD runs with 200MHz and I
>>> have also seen AS7C33128 with 200MHz. And the sample rate is 100MHz.
>>>
>>>       
>> Speed is mainly limited by the CPLD. 200MHz is an ideal situation with
>> very simple (or no) logic implemented.  We need 16-bit trigger, 2x
>> 17-bits counters etc. and it slows it down. It was very difficult to
>> make it run at 100MHz.
>>     
>>> 4. Are there alternatives for the oscillator? I have no old PC
>>> mainboard where I could take it from.
>>>       
>> I don't know, but it has shown up that most 5V oscillators worked at
>> 3.3V too. Try it with standard 5V oscillator, which is not difficult to
>> obtain.
>>
>>
>> Jan
>>
>>