On 01/15/2012 05:48 AM, Chris Albertson wrote:
On Sat, Jan 14, 2012 at 4:32 AM,<[email protected]> wrote:
I have no expertise when it comes to filter design or programming PIC's or
other micro controllers. But I know what works for me. For 11 years I have
been using Shera controllers with very good results. (I still have some new
assembled extra A&A boards, if any one is interested, please contact me
off list) Over the years I have made hardware work around's and made my own
boards ending up with 120 and 240 samples and 100 MHz clock in stead of 24
MHz. Over time chips are harder to get. The solution is an Altera MAX 3000
gate array and that input circuit can be implemented on a $ 2 100 MHz
version or $ 5 200 MHz version using either a 100 MHz or 200 MHz clock. That
circuit works with the present Shera PIC but that is a 28 pin $ 4 device.
Since in this application the controller does not have to be all things
for all devices it would make sense to use a PIC16F688 or any other 14 pin
device.
Have you thought about putting the PIC _INSIDE_ the Altera FPGA?
It's a common trick to implement a microcontroller in the FPGA and you
can get the code for just about any CPU core online. Here is an
example of "virtual PIC":
http://www.embeddedtronics.com/pic_core.html
If the PIC fits inside then that is one less chip on the PCB. The
example above found that could run the virtual PIC a little faster
than a real pic so you don't give up any performance
A short notice on embedded CPU/MPUs into FPGAs. Using PIC or AVR might
be tempting, but I consider any clone "dirty" from a rights perspective,
MIPS for instance have been very protective on their side, so has ARM.
So far has the SPARC been the only big one being accepted in their
LEON-x variants that I know of. We be sad to see the cotton industry
level being smashed by the big firm lawyers.
So, either using the OpenRISC variants or similar. There is loads of
CPUs on the OpenCores website, but just because they are there do not
think they are free to use if they are clones of commercial stuff.
I would either use one of the FPGA vendors CPUs and then write the core
in C, or use a free CPU.
I could also roll my own CPU, as I have already done before, but
building a tool-chain including GCC is a bit of home-work. For my
application I haven't bothered, but it is tempting to get C capabilities.
Then again, if someone could show that the PIC and/or AVR is free to
clone in FGPA, by showing a clear statement from the respective
technology holders, then that would be a way forward.
I've done this analysis before, and so far I have not seen any
comprehensive open analysis covering these aspects.
I fear that this is way off topic for this list, so I propose that this
aspects is continued on another list, such as the FPGA-Synth list, which
faces essentially the same problems.
Cheers,
Magnus
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