On 21.02.17 01:13, Gene Heskett wrote: > If perchance this magic new device has some fast gpio, and a spi driver > could be written for it, the 7i90HD with spi firmware might be usable?
The on-board Intel Curie microcontroller, which provides the Arduino 101 compatible extra stuff, has "SPI Flash" listed as an "Other Interface": See: http://www.udoo.org/udoo-x86/ Perhaps more guaranteed to be really hard real-time; the quad-core main cpu has "up to 20" GPIO. That'll depend on what else we want to use pins for, clearly. It ought to be feasible to ferret out some Linux SPI foo out there in the googleverse. (Some time to faff with it is then item 2 on the agenda. (Well, 3 until the board arrives and I push some Linux into its brain.) > That spi bus protocol is a 32 bit, 4 byte packet going each way, with a > 32 megabaud transfer rate in and out of a Raspberry pi 3b. Thats no > slouch in the ability to do realtime control. Said another way, if the > cpu power was there, one could run the servo-thread much faster than 1 > kilohertz. Without the hal calculations required, an update rate of 4 > megahertz for every bit of the 7i90's 72 pins of i/o could be achieved. > > LCNC is sitting idle out there, and the pi doesn't isolate the isolcpus=3 > from being monitored by htop like it does on the x86 hardware, and the > idling rtapi task is using 13.2% of cpu-3. So I can add quite a bit of > processing overhead in my .hal file's yet before it actually > gets "busy". Or run a servo-thread at 5 kilohertz. Well, it's X86. So we have to hobble 3 of the 4 cores, but not on ARM? > Yes, you'll use a pile of ferrite snapon chokes, and pay real attention > to a single bolt grounding system, but once thats understood it seems to > Just Work(tm). And that card is only a tad over a $60 bill on your > front deck here in the USA. And its interface versatile, offering the > same i/o features at the slower EPP parport rate if its a true 3.3 volt > EPP port. But on the pi, the spi is only 4 signal wires not counting the > 8 commons, and still faster than the parport version is. I have no clue > if a true EPP parport driver has even been written for the pi's. It > doesn't have one natively that I'm aware of. The Udoo X86 isn't as cheap as a Pi, and I added a good sized SSD to my order, which didn't help. Their promotional video claims it's a _heck_ of a lot faster than the Pi, but they may be focussing on graphical performance. Erik ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
