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. > 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-generic-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 -- Nicklas Karlsson <nicklas.karlsso...@gmail.com> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
