Re: emc-fpga.txt

[Ray <rehenry-at-up.net>]

Keith

I don't understand much of what you said but there are a couple of things
that I can respond to.

The price for the capability sounds terrific.  Particularly for those who
want to do part of the work themselves and don't mind a bunch of wires to
and from the PC.

Yes the software, once it is written and tested, would be bdi able.  We
would just need to compile the software for the same kernel and file
structure that the bdi uses and build an RPM that we can put in the
linuxcnc.org dropbox for people to download and install on their bdi
machine.  Then when the next release comes along we can include it on the
disk.

In fact, I'm thinking that we might do similar RPM's for several of the EMC
machine definitions.   Then users could install whatever set that would
match the machine they are setting up.

Ray

On Thu, 17 May 2001, you wrote:
> Hello All.
> 
> I am working on a prototype board that may be of interest
> to EMC users.  It is an ISA WW based on a Xilinx 4005XL
> FPGA at 50 MHz, running four 12-bit delta-sigma DACs to
> +/- 10 volts and four quadrature encoder inputs.  The
> only controller is a Pentium II 233MHz dual booting RHLinux
> 6.2 and DOS 6.22.
> 
> Since an FPGA is in-system-programmable, the internal
> 'electronics' can be as easily changed as the software.
> It is currently I/O mapped to 0x300 .. 0x31F, 16-bit only
> access with control/status junk in the first 16 bytes
> and 16-bit encoder/dac pairs the remainder.
> (yes, memory mapping would be faster... ISA yuck)
> It generates a heartbeat irq 7 every millisecond.
> 
> My cost for the FPGA was $27; better ones are available
> for $15 with 20k+ gates -at-120MHz, but not wire-wrappable (pfqp).
> I estimate an ISA board with such a system would have
> a parts cost of under $50; so maybe $150 assembled&tested.
> 
> My question for the EMC experts is:
> 1.  How difficult would it be to modify the EMC internals
> to support such a system as described above.
> Would it be BDI-able?
> 2.  Would EMC be able to make any use of the FPGA-specific
> additional abilities - such as direct velocity measurement,
> sub-quarter count encoder interpolation and the direct
> numeric interpolation of splines?
> 
> Good day.  --krb