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Josť A. Ruiz
06/01/13 12:53
Read: 1117 times
United Kingdom

#189844 - Agreed
Responding to: Michael Karas's previous message
I'm going to spoil the argument because I agree with you :) An off-FPGA CPU will be the right choice in just about 100% of the designs; and for that rare case where you do need a soft core, there are plenty of commercial 8051 out there, all of which are better and more reliable than any homegrown one.

A core like this only makes sense as a hobbyst project. I made this one during a long spell of unemployment. It was fun and rewarding but the end result is flawed in many ways; It could have been much better given the development time available, but I built it at a laisurely pace without much thought for the end product. I was actually surprised when I finished it and only published it so that I could mention it in my resume, to be totally honest.

So this particular core is not a good case for the soft-vs-hard-CPU argument. However, as I said, I think soft CPUs do have their place: tightly integrated, deep into some custom logic design. Such a system with its CPU built in is self-contained and thus easier to port to other boards or reuse in other designs.

Another attractive use case might be building an interconnected crowd of small CPUs as an alternative to a large CPU running a multi-threaded application on a RTOS. This can be done more conveniently inside an FPGA (*really small* soft CPUs that can be programmed in C are hard to come by but that's another story).

In short, as someone said in this forum, a soft core will go into places a hard CPU will not. That is their biggest (and maybe only) advantage, I think.

List of 23 messages in thread
OCD for FPGA core      Josť A. Ruiz      06/01/13 03:48      
   Serial-to-EC2 reverse engineering      Josť A. Ruiz      06/01/13 06:12      
   C2spec.pdf      Jim Granville      06/01/13 06:36      
   Reality Check......        Michael Karas      06/01/13 08:24      
      Agreed      Josť A. Ruiz      06/01/13 12:53      
         multi-threaded      Jim Granville      06/01/13 16:54      
      FPGA and soft cores      Oliver Sedlacek      06/03/13 02:20      
         Yes ... but which debugger?       Richard Erlacher      06/03/13 10:48      
            Actually no      Oliver Sedlacek      06/04/13 01:55      
               Who's "they"      Richard Erlacher      06/04/13 12:48      
               I wouldn't use FPGA unless I need more than just the core      Richard Erlacher      06/07/13 14:50      
                  FPGA on-chip debugging redundant?      Josť A. Ruiz      06/14/13 02:49      
                  debugging embedded processors        Andy Peters      06/25/13 18:56      
                     That's good to know.      Richard Erlacher      06/26/13 11:13      
   nice idea      Maarten Brock      06/02/13 07:03      
      Von Neumann first      Josť A. Ruiz      06/02/13 10:23      
   if that were the case ...      Erik Malund      06/03/13 15:19      
      Poorly chosen acronym...      Josť A. Ruiz      06/14/13 02:59      
         On Chip Debug is common        Jim Granville      06/14/13 03:44      
            On Chip Debug *is* a very good idea indeed!      Andy Neil      06/15/13 13:44      
               PC        Maarten Brock      06/15/13 14:09      
                  PC        Michael Karas      06/17/13 06:55      
                     PC        Oliver Sedlacek      06/18/13 02:19      

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