Matt Shaver wrote: > If I spend one more minute thinking or writing about copyright and > licensing issues I'm going to give myself a brain tumor, so I'd like to > do something useful for a change :) > Yeah, I know, I thought about this for about 3 minutes and had to stop! > GP Orcullo has got a project (PICnc) where he attaches a PIC32 > "auxiliary processor" to linuxcnc on a Raspberry Pi through the RPi's > SPI interface: > > http://www.raspberrypi.org/phpBB3/viewtopic.php?f=37&t=33809 > > (his writeup on linuxcnc for the RPi is also invaluable): > > http://wiki.linuxcnc.org/cgi-bin/wiki.pl?RaspbianXenomaiBuild > > I'd like to do something similar, but using an FPGA in place of the > PIC32 to create the equivalent of a Mesa 5|6i25 for the RPi. I know > Peter at Mesa has some plans for an SPI version of his "Anything I/O" > system, and we'll need an hm2_rpspi component to use it in linuxcnc. > The PICnc project (above) has code that demonstrates the use of the SPI > on the RPi. > > I did make an adapter board to connect my USC/UPC boards to the original Beagle Board. It has 1.8 V I/O, so I used some SN74LVC8T245DBQR bidirectional level translator chips to convert. I wrote some primitive code to demonstrate it could talk to an EPP target device, and it all worked. If anyone wants to see how I did it, I can provide the schematic and the rough driver. With a little driver code it provides pretty much everything a PC parallel port can do. > Is anyone else working on hostmot2 over spi? If not, does anyone have > any advise or pointers on how to go about this? > I think the best way would be to make the PRU do the SPI or some other serial protocol. The Pi also has a PRU, right? Otherwise the BeagleBone might be a better platform. They have just upped the memory on the Bone. The fastest thing might be a byte-serial interface. You could make it look sort of like EPP, with an addr strobe, data strobe, R/W signal and 8-bit bidir bus. You could probably do 10 megabytes/second over a short cable. A single-lane serial protocol could probably go almost as fast.
Jon ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
