Lyle You forgot to mention the FUN??? of adding, instantiating and debugging packages from third party sources too lazy to document - hi!
Phil, K3IB ----- Original Message ----- > > There is enough information there to tell you the main parts on the > board. You then should go to the manufacturer's website and download > the data sheets and related materials regarding the specific part (the > FPGA, for example) as well as the related information (Cyclone family > manuals and app notes, the Quartus software and manuals, etc.). Work > though any tutorials or examples you find on the software. Quartus is a > very powerful tool, but it isn't just "push button" software. In the en > d, if you are doing anything other than downloading and using the work > someone else did, you will have to spend some time learning the tool. > > The same thing applies to the Cypress USB interface microcontroller. > > When learning to work with FPGAs, there are a number of general things > to be aware of. > > If your background is using discrete logic chips, like 7400 or 4000 > series (yes, that dates you as well as me) you'll quickly discover that > different approaches are required. FPGAs typically have very limited > "global clock" resources and logic should usually be designed to be > synchronous to the the clocks. Asynchronous logic approaches can work, > but they are much more difficult. You can't stick a capacitor or an RC > network to suppress a 2 nsec wide glitch, for example, and the FPGA > internal logic is fast enough to care about that glitch. With the > limited clocking, it is much harder to have various counters and shift > registers working at different clock rates; you have to build clock > qualification circuits to enable effective division. > > The FPGA equivalent is to do a syntax check and correct any errors > there, then run a simulation of the input (if using VHDL or Verilog) to > ensure the logic design seems to be OK. > > You then compile it, and then run the simulation on the output of the > compiler, because it will sometimes (usually?) infer things from your > statements that you did not intend. > > After place and route, you back-annotate and simulate again. Then you > download into the logic, and see if it works! Then you try and > understand why it didn't!!! > > Also, note that different FPGAs from different manufacturers have > different resources. Sometimes there are preferred ways to write the > VHDL or Verilog to perform a specific type of function. Pay attention > to any tips or hints or coding style information particular to the FPGA > and compiler you are using. Just like writing lean software versus > bloatware, you can write a logic function in different ways and the > difference in results can be *huge*. Sort of like nested if-then-else > versus a case statement. Sometimes one is better than the other based > on the underlying architecture. > > For debugging any but the most trivial designs, a logic analyzer is > almost indispensable. Quartus allows you to embed one in your design, > called SignalTap, if you are willing to let Quartus report back to > Altera what sort of designs you are doing and all sorts of other > "statistics." If you find this intrusive, you have the option to turn > off SignalTap. I am nor sure if the Xylo USB interface supports > SignalTap back to Quartus or not. > > Otherwise, you have to write your own logic analyze rand insert it into > the design, bringing signals out to pins you can probe with external > test equipment. Or maybe your logic design is already pushing the limits > of the FPGA and there is no room inside for SignalTap or your own logic > analyzer module. > > I recently purchased a low cost logic analyzer to supplement my higher > end analyzer, and find it useful for FPGA projects. YMMV, no financial > interest, etc. <http://www.pctestinstruments.com/> > > FPGAs are powerful, and flexible. They are the hardware equivalent of a > CPU. And like a CPU, learning to tame them, feed them, and train them > to do what you want is an experience that can be exhilarating as well as > extremely frustrating. Persevere! > > 73, > > Lyle KK7P > > > _______________________________________________ > FlexRadio mailing list > [email protected] > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >
