Gene Heskett wrote: > On Sunday 04 January 2009, Jon Elson wrote: > >> Gene Heskett wrote: >> >>> On Sunday 04 January 2009, Peter C. Wallace wrote: >>> >>>> On the other hand you can do a lot with a embedded 32 bit processor in a >>>> FPGA (the ZPU for example uses about 20% of a 400K SP3, runs at ~ 100 >>>> MHz, is BSD licensed and has a GCC toolchain) >>>> >>> Which again, sounds like a plus till you said 100mhz. That might do for >>> servo driven machines but I'd guess it won't run steppers at usable speeds >>> will it? >>> >> Well, if you are embedding in an FPGA, then it costs NOTHING to add in a >> hardware step rate generator! >> That's the whole BEAUTY of putting it all in an FPGA, if there's an >> important function the CPU can't satisfy, add additional hardware to do it. >> > > It also means a familiarity with FPGA compilers, something I have no clue > about. And at my years, no real incentive. I probably won't last long > enough to put it to use. > > >> But, EMC is very tied to doing everything in floating point, and the >> FPGA CPU IP's generally don't have this. Most FPGAs that are not >> designed from the ground up for DSP don't have the dedicated multiplier >> logic to do well at this, either. If you want to do things with FPGAs, >> it turns out that the smaller devices are QUITE reasonable in cost, but >> the larger ones become very expensive. There are some really incredible >> Xilinx chips out there in their Virtex series, but they cost $7800! Can >> you imagine a single CHIP for that price? (Now, I'm not saying you need >> one of these to put a CPU in, but you could easily be talking about a >> $200+ chip for this. A $20 Arm9 starts looking a lot more affordable then.) >> > > I had wondered about that too. Does that arm9 have an fpu? And if it does, > is it wide enough for emc? > Aty least some chips do have FPU. The NXP data sheet for the LPC3000 touts it. I don't know about others, like the Atmel doesn't seem to show an FPU.
Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
