On Wednesday 03 May 2017 23:44:02 Jon Elson wrote: > 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 8825 does what? I need to take another look at your site I guess. > The BeagleBone is $55, And how many cores & how fast is its arm? > 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.) That sounds quite a bit more palatable. > > 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. How fast can they run? Thanks Jon. But I'm past due to get requainted with my pillow. Tomorrow. With luck, dd will have imaged the only working u-sd card I have left that will boot that pi. That was tricky as I had to expand a 3+ gigabyte partition on a terabyte drive to 850Gb, without losing any data already on it. Then I have room to image the sd card so I can make more copies on 4 other cards that won't boot anymore. > 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 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> ------------------------------------------------------------------------------ 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
