If you are trying to get data from a Pi to an Arduino at a reasonably fast rate. Use USB. The Arduino has built-in USB as does the PI. USB is great because it is a balanced, differential signal. It is way-faster then you need for this purpose. It is also very easy to use from the software in both Arduino and Pi. The Arduino software sees the USB cable as a serial port and the Pi can see it the same way
If you are worried about packet delay and unpredictable latency that look into using USB's isochronous transfer mode. On Thu, Aug 9, 2018 at 8:32 PM Greg Bentzinger via Emc-users < [email protected]> wrote: > > > Greg - To Gene - and list > > > If the RPi can use SPI over a 250mm length cable at rated speed then it is > a great option. > > No? How about a 150mm cable? > > If the signal can't get off the host PCB and to the target PCB reliably > then the whole issue is a non starter moot point. > > Maybe if there was an off the shelf adapter PCB to rig a hat sandwich. For > 90% of users PCB level mods are beyond what they signed on for. > > SPI is faster than needed which is nice to have extra available free time > in the loop. > > But MACH 3, other than smooth stepper users was almost all para port. LCNC > proved it could drive parallel ports just fine. Higher level controls Like > Pico Systems and Mesa ECP/EPP based FPGA cards have proven that an ECP/EPP > connection is plenty effective speed wise. > > > For my mill retrofit I went with a small pile of Mesa cards starting with > a 5i25/7i77 with several additional SSerial cards added to the mix (mega > overkill, and probably not really needed) > > I still have a 7i43 I bought way back, and I have a lathe conversion that > has been on a back burner for a few years. I was thinking of driving the > 7i43 with a new/old stock DM510 I have had on the shelf NIB long enough > that any warranty has long expired. Sadly the DM510 is actually less > powerful than the RPi, only thing in the DM510 favor is I can stuff it with > 4gb ram. > > I have renewed my interest in the Pi because I'm looking at some simple > applications which using the Pi as the front end driving an Arduino with > GRBL is plenty. One application is a powered feed with auto reset for my > horizontal bandsaw, a second axis could be used to auto feed the stock for > the next cut using a vise clamped/unclamped sensor switch to > inhibit/resume. Another RPi + Arduino GRBL is a stand alone programmable > 4th axis indexer for manual milling - plus having connectors that would > allow bypassing the Pi/GRBL and driving the stepper (with encoder feedback) > from LCNC. > > Another project that is just on the wish list at this point is a 5 axis > tool grinder, but it might become 8-9 axis if I include programmable form > wheel dressing. (bring Whiskey and Asprin) > > Currently all conversions are on hold as I am trying to make space to > shoehorn in the machinery I purchased from my Uncles Estate. I have a Okuma > LK 350mm lathe, Bridgeport, another horizontal bandsaw and a Harig 6x18 > Surface grinder. Been so much rain the soil is too soft for the forklifts > to unload. So delivery keeps getting pushed back. Thankfully I'm not > backlogged currently because after the machines are in, then I have to go > back to the old site and remove the wiring and phase converter and install > the outlets at my shop. > > Greg > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
