On Mon, 13 Jan 2003, [iso-8859-1] Tomasz Sztejka wrote: > --- Manuk Shemsyan <> wrote: > Hello everybody, > > > > > > I work for a company specialized in CNC system design. Most > (...) > > Currently I work on some modules' Verilog models and would like to > > know other opinions on this theme. > > > > Thank you, > > Manuk Shemsyan, > > > I would consider placing a DSP or one of faster microcontrollers on > board in addition to FPGA to lower costs - huge enough FPGA to handle > every task + processor task (something like showing data on display, > communication and etc. ) will be costly I think. I would use FPGA to do > things which must be done very fast (PCI connection, fast encoders or > whatever) leaving less time critical tasks to microcontroller. It would > be a nice thing for IP cores users to have a choice between software > and hardware core realization for such a mixed systems. > > regards, > Tomasz Sztejka We considered doing that (External CPU + FPGA) on our low end Servo motion controllers, and even laid out a card with an ARM CPU and a FPGA, but it turns out that its easy to get enough performance from CPU embedded in the FPGA to do 8 Axis of motion control at a 15 KHz update rate. We did have to do all the code in assembler though. If you use an external DSP you might consider the TI one with the built in PCI interface. Using a DSP also gives you access to better development tools. One advantage of doing everything in side the FPGA is that you can tailor the CPU instruction set to the task at hand (for example, something we end up doing a lot is bounding a signed 32 bit number to a signed 16 bit number. Our CPU has an instruction for doing that...) Take a look at www.mesanet.com/softdmc.pdf for manual of a 4 axis servo motion controller embedded in a ~$20 FPGA. The VHDL source for the hardware is available at www.mesanet.com/4i34.zip. That zip file also includes an earlier servo controller based on Ken Chapmans excellent KCPSM. That earlier servo controller includes the VHDL + assembly language source to the KCPSM code... Peter Wallace Mesa Electronics |