On 20-11-2012 20:54, Michael Haberler wrote: > I dont want to curb your hopes too much, but I said 'GladeVCP+HAL standalone > applications' and meant to say 'HAL only' - i.e. no Gcode, no task, no motion > - more loudly > > that works and I can recommend looking into especially if the application > isnt very time critical (I get something like 45uS latency on the Pi with > xenomai) > > I do use the Pi as an exemplary platform to test configure and build; I dont > expect to use it for CNC purposes myself and I'm not investing effort > > dont waste too much time on seeing a Pi as €35 CNC platform just yet - it's > pushing the limits (gut feeling, without having tried I'd say this is outside > the Pi's capabilities, and the I/O interfacing capabilities arent that plush) > > I'd rather look into a BeagleBone or so for real I/O; still soft stepping is > a bit meager on ARM's without resorting to tricks like Sergey did in miniemc2 > - which is btw worth picking up, but not necessarily by me ;) in case of the > BeagleBone it would mean 'program the RT hard stuff in the extra 'realtime > RISC cores' which doesnt look like a weekend project either > > -m >
Michael, Now you've got me interested! Not in the Pi part (that hype will probably pass [let's start a good old flame war ; ) ]) but the BeagleBone part. If you look at my BeBoPr project (https://github.com/modmaker/BeBoPr), it's doing what you suggest here: The hard real-time stuff (step generation) is running on one of the PRU coprocessors and Linux is doing the non-real-time stuff. In fact I think my stepper code is doing more than is needed for LinuxCNC, but maybe some features are still missing. I haven't spent much time investigating the possibility of running EMC on the BeagleBone, but it has been one of the things on my todo list. The biggest obstacle until now has been finding a proper real-time kernel. I've been waiting for a long time for a Xenomai based kernel, and now that RTAI is (finally) declared dead, the time might be right to jump the bandwagon ; ) As I'm interested in LinuxCNC myself (I've been using it for a while, years back), I might volunteer for the PRUSS code once a working Xenomai based ARM Linux kernel and EMC2 port is available. Writing and debugging PRU assembly is not always fun and certainly not a weekend project, but I've been doing it for longer than I dare to say, and can re-use a lot. So, any volunteers (with stamina) for the Linux part? -- Bas > > Am 20.11.2012 um 17:40 schrieb Anders Wallin: > >> Good news! >> I've ordered a Pi (Farnell re-directs to a local distributor), but the >> delivery-time seems to be 3 weeks right now(?) >> >> It seems that the SPI interface will be most useful for high-speed IO. If I >> understood correctly the Pi supports only two separate chips on the SPI-bus, >> but on IRC PCW mentioned that SPI is possible on the GPIO-pins also? For a >> servo-controlled machine I guess a microcontroller and/or FPGA on the SPI >> bus could read encoders, output PWM, and do IO. One would then need a >> HAL-driver that is capable of communicating the relevant data over SPI every >> servo period (1ms or so). Do you think this HAL2SPI driver will be easy or >> hard to write? >> What about stepper-machines? Is it enough to communicate a stepper velocity >> over SPI to dedicated step-generation hardware? >> >> In addition to cnc use I'm also interested in stand-alone operation with a >> touch-screen, for example this one (HDMI display, USB touchscreen): >> http://www.lilliputuk.com/monitors/open-frame/of701-2/ >> >> Something that boots directly into a Touchy-like custom UI-panel and can >> set/watch/plot/etc. HAL-signals would be really nice. >> >> Anders >> >> On Tue, Nov 20, 2012 at 4:47 PM, Michael Haberler <mai...@mah.priv.at> wrote: >> I just verified this combination works, for the standard Raspberry Raspbian >> kernel 3.2.27+ with Posix threads (aka 'simulator'), and with Xenomai 3.2.21 >> for somewhat better performance >> >> both remote X Display and local console work >> >> this is the rtos-integration-preview1 branch; the only part needed disabling >> was the GladeVCP sourceview widget which is lacking the underlying modules >> >> currently the only hardware driver supported is hal_gpio for wiggling some >> pins; the serial, i2c and SPI interfaces would be possible further >> candidates, mungkie did some initial work on these >> >> >> I'll see whether I can come up with an SD card image ready to go with all >> the parts (xenomai + userland support + linuxcnc prerequisites + linuxcnc >> built) >> >> Axis, touchy and friends are still untested >> >> >> - Michael >> >> >> > > ------------------------------------------------------------------------------ > Monitor your physical, virtual and cloud infrastructure from a single > web console. Get in-depth insight into apps, servers, databases, vmware, > SAP, cloud infrastructure, etc. Download 30-day Free Trial. > Pricing starts from $795 for 25 servers or applications! > http://p.sf.net/sfu/zoho_dev2dev_nov > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
