On 05/03/2017 09:28 PM, Gene Heskett wrote: > > The killer in the beaglebone soup is the cost of the "capes". You've over > $200 plus psu's etc before it can turn 2 motors at the same time. Umm, the CRAMPS board is $79.95, and I sell the 8825 drivers for $5 each, but I get them from China for about $1.30 each. The BeagleBone is $55, but there are some that have the HDMI pulled out for $39 from SEEED, I think. The CRAMPS can run 6 motors, plus 5 PWM controlled DC devices, plus 6 limit switch inputs and 4 analog inputs. (Disclaimer: I make the CRAMPS boards.) > I > don't begrudge the guys trying to make enough to buy their beer, but a > 7i90 for a bit over $60, simply blows most of the capes I've looked up > into the next drainage. > > The spi bus out of the pi runs at 32 megabaud, sending 4 byte packets 4 > bytes at a time with an extra stop bit between 8 bit bytes. Thats the > equ of a 32bit word at 4 megahertz. The parport would have to run at 8 > megabytes/second to match that amount of data in that same amount of > time. I think... At any rate, that's an order of magnitude faster than > the parport can legally do it, it just does not have the ability to > deliver the slew rates down the cable that would need. 10% of whats > needed is all that is legally available Does linuxcnc have the ability > to work over that slow a com channel? Seems like that would be pushing > our luck. > > And, the Beagle has 2 (I think) SPIs that can be brought out to external pins.
Jon ------------------------------------------------------------------------------ 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
