[time-nuts] Controlling FEI 5680A

Jim Lux jimlux at earthlink.net
Mon Jan 16 10:07:12 EST 2012

On 1/16/12 2:44 AM, Attila Kinali wrote:
> On Sun, 15 Jan 2012 11:27:27 -0500
> paul swed<paulswedb at gmail.com>  wrote:
>> FPGAs are generally intended for the mass market with a steep learning
>> curve. Though they can be pressed into whats of interest to time-nuts it
>> simply seems like a overly complicated technology and method for a non-mass
>> market solution.
> Actually, they are not. In the mass market, you dont want to use FPGAs
> due to their high cost. As soon as you produce more then 10k pieces (in total)
> you start thinking about doing an ASIC.
> And the learning curve isn't any more steep than for learning how to
> work with a uC. It's just that most people know already a bit of programming
> which makes it far easier to learn enough C to do something with a uC.
> At the same time, programming experience makes it more difficult to
> learn VHDL/Verilog, because people think it works like a programming language
> which it definitly does not.
> But yes, you are right. An FPGA is probably not the right thing. Not because
> it is more difficult, but rather because there are less tools and less
> documentation available. Hence making it more difficult for the hobbyist
> to handle FPGAs than uCs.

Precisely so, particularly the tools.  FPGAs (especially bigger ones, 
not just PALs and CPLDs)  have been around about 20-25 years. I seem to 
remember going to some Xilinx seminars in the late 80s, when they were 
proud of their simulated annealing place and route running on a 286.

So they've had only a few decades of development on the tool chain, 
compared to more traditional high level languages, where the basic 
computer architecture has been around 100 years, and compilers have been 
around for 60.  There's also more "genericness" by now in the VonNeumann 
Model programming world: there must be 100 different CPU families out 
there, and we've converged to only a few basic programming models. 
THere's only a few FPGA architectures out there, and there's really only 
two different languages Verilog and VHDL.

And as Attila points out, both of those look superficially like ordinary 
programming (particularly VHDL) and you can even write "sequential 
programs" in them, but the underlying hardware isn't even remotely like 
that, so you are seduced into a very non-optimal design style.

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