On Wednesday 27 March 2019 14:03:33 Nicklas Karlsson wrote: > On Wed, 27 Mar 2019 19:12:48 +0700 > > TJoseph Powderly <tjt...@gmail.com> wrote: > > ( list apology, I seem to have replied to posters rather than to the > > list, and several times :-( > > > > re SPI comms Linuxcnc SBC microcontrollers ... > > > > it has been said on this mail list, > > that SPI is a good candidate for a bus technology to work _with_ > > realtime. > > Maybe not as a bus but chip select between devices over a short > distance work. Isolation is possible but delay may cause problem at > high speed. If drivers are kept close together and there are not to > many of them which likely to be the case it is a good candidate. > > CANopen is available for ordinary CAN networks and over Ethercat. SDO > protovol may be a very good candidate for configuration to get a more > or less standard format, *.eds files may be used as a standard > dictionary format, expedited transfer of up to 32 bit at a time is > relatively simple to implement, to add a sequence number might be a > good idea so that severel messages could be on the the they thru the > system but for configuration to wait a short while is OK since there > usually only is a need for a few numbers. I have som code is somenone > need it. PDOs are simple if harcoded, mapping and communication > parameters are harder but may not be needed for a working system. > > SPI is very common on Micro controllers, cheap and fast but only over > very short distances, there certainly are limitations. > Qualify very short distance to include up to 8" long although it wasn't as bulletproof at a lower speed as I was using 8" pin to pin jumpers and no termintors. Now my cable is a legit ribbon and about an inch. And Jon E's little terminator board adds a little under an inch to that. At that distance, its bulletproof.
> > heres some work in that vein (maybe overlooked) > > > > yeltrow's work: > > a generic spi hal module so you can use other SPI devices ( rpi, > > arduino, mcp23s17, ENC28J60, theres a lot of spi stuff to hang onto > > such a bus ) > > https://www.forum.linuxcnc.org/24-hal-components/28851-spi-bus-gener > >ic-driver-and-st-l6480 > > > > the files are on the forum for members > > linuxcnc-upload-2015-12-03.tar > > > > erste's work: > > for ethernet circumventing usb ( via spi > > interesting as spi and ethernet seem to be future avenues > > http://erste.de/ethraw/README > > > > theres other efforts but less coupled to the spi grail > > > > tomp > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
