Re: gEDA-user: PALs GALs and SPLDs going the way of the Dodo?

[Gabriel Paubert <paubert@xxxxxxx>]

On Fri, Mar 27, 2009 at 03:57:18PM -0400, Ormund Williams wrote:
> Hi All
> 
> I'm designing a circuit and needed a few gates, 8 3-input AND, 4 2-input
> XOR, 10 inputs and 8 outputs, it seemed to me that this would fit
> perfectly into a 16v8.  Now the last time I used SPLDs was '98 and it
> annoyed me back then that no open-source tools existed to support
> development now it looks like this segment of semiconductors is dieing.
> I just went through the latest issue of Circuit Cellar and there isn't a
> single add for a universal device programmer (nice article DJ).  None of
> the few manufacturers left seem to be making any improvements to these
> devices, like chip scale packaging or low voltage (<3.3v).
> 
> Am I correct in thinking that it would be unwise to use these in new
> designs?

Unless you want to pay outrageous prices at Rochester or similar.
 
It also depends on your needs: if you think that you are going to 
produce a large series, avoid them. For a one time run of a few
units, why not if you find them through www.findchips.com or similar.  

> Do you use SPLD? What do you use to program them? How about
> the ISP versions?

Have you had a look at Lattice (www.latticesemi.com), they still
sell them on their online store (apparently through Mouser) and there
are quite a few in stock. There are even some low power models
still available at Mouser.

ISP versions are nice for somewhat complex designs, when you already
have a JTAG chain on your board and think that you might need 
reprogramming them to fix bugs; obviously real hardware designers
never need this, bugs are purely a software concept :-)

Besides that, at least from Lattice, only the ispGAL22V10A is worth 
considering, the non-A need over 100mA even when idle. The A version 
exists at 1.8, 2.5, and 3.3V supplies in a 32 pin QFN package (5x5mm). 
Mouser has some of them in stock. 

> 
> Thanks for indulging my rant.

No problem, I'm also a bit fed up that there is virtually
nothing left between bus buffers and multimillion gate FPGA
which need 3 power supplies. I don't mind occasionally using
a hammer to kill a fly, but using a nuke is too much and users
complain from radioactive fallout :-). 

For very simple things (a Schmitt-trigger to drive a status 
LED here and there in the middle of an analog design) I use 
1G series but they are not dense in terms of supply/ground 
pin per gate so routing becomes a nightmare or 4 layers+ 
are needed.

	Gabriel


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