On 9/14/2013 3:58 PM, John Prentice (FS) wrote: > Greetings > > I have run a real machine and made chips with the BBB and MachineKit > package. And very impressive and promising it is even with a 750 kB > engraving job. Trying to get beyond the basic integration shows my poor > Linux fundamentals :=(
Video or it didn't happen!!! I want to link to a YouTube video of a BBB cutting chips on my blog! :) > (a) Having used the bootable SD card I can remove it and boot the original > system from the BBB eMMC but other SD cards will not show up under it in a > "df" listing. I wanted to make a new bootable SD to work on while also > retaining the known simple configuration that works. Is this change to > original system behaviour expected and if so how is it reversible? You are probably hitting a software issue with the BeagleBone kernel which generally doesn't like to recognize the SD card if you've booted off the on-board eMMC. IIRC there are some patches that went by on the mailing list recently (BeagleBoard device-tree updates on the Linux-OMAP list) so perhaps this will be fixed soon. In the meantime, if you want to use an SD card when booting from the on-board flash, you need to use a USB card reader, not the on-board uSD slot. :( > (b) I am bemused at where the magic numbers connected to steppin and dirpin > in HAL come from (e.g. the comment the actual pin used and 0x4c make no > sense to me: > > #P8.43 PRU1.out2 P8.43 is pin 43 on the P8 header of the BeagleBone. > setp blah blah .stepgen.00.steppin 0x4c 0x4c is the kernel GPIO Pin numbering scheme + 32 (so that zero means don't twiddle any actual pins). In this case: 0x4C = 76 (dec) = (32 * 2) + 12 = GPIO bank 1, bit 12 > I have looked for a pattern with this BeBoPrBr example and all the tables > including considering the 0x800 bit and the excess 32 coding for PRUs but > cannot see any pattern. I want to add another stepgen to drive the machine > spindle. The B axis seems in place in the .dts file but what goes in the > HAL? None of the existing configurations support more than 4 axis, but the BeBoPr with a bridge does have step/dir lines for a B axis. In HAL, you need to add another step/dir generator to the pru_generic component (num_stepgens=5 in the ini file), then map it's I/O signals using the kernel GPIO number + 32 convention. Other than the I/O lines, the rest of the signals are fairly standard for LinuxCNC (ie: commanded position & feedback). The HAL values should be: B_Dir = GPIO bank 0, bit 5 = 32 + 5 = 37 B_Stp = GPIO bank 0, bit 4 = 32 + 4 = 36 You will also need to remove these pins from the hal_bb_gpio driver (remove the 217 and 218 entries from output_pins) so the PRU and the GPIO driver don't try to control the same I/O pins. > (c) Straight Linux problem: I cannot work out how to Mount USB sticks in the > running system under XFCE/Thunar except logged in as root. Thunar says Not > Permitted and unlike under Gnome you cannot run things like Thunar or medit > with sudo from a Terminal. Google was not my friend on this occasion giving > lots of recipes in fstab but no explanation of principles. Use sudo mount /dev/sdx /mnt/wherever at the command line. > (d) Similarly I can only shutdown/restart Linux by logging out of linuxcnc > and logging in a root as the buttons are greyed out when user linuxcnc. sudo halt > (e) finally and this may be a step too brave at present, I wonder if anyone > has tries/succeeded to run the filesystem off a USB drive (probably a > harddrive) using pivot root. The hope was to get better performance, > particularly in development systems as I would like to install some user > Comps. I believe Robert Nelson (who wrote the scripts I use to build the kernel and the images) uses a USB HDD on his build systems, but I'm not sure if those are BBB's or something else (like BeagleBoards). There are a variety of USB issues with the BeagleBone and the 3.8 kernel, so I'd be careful if you want to go this route (ie: make frequent backups). When I am worried about size and speed, I have used remote NFS mounts with excellent results. This also keeps the data on a "real" system (in my case, a SAN back-end with hardware RAID) instead of a single disk attached to the 'bone. Holler with any other questions! -- Charles Steinkuehler char...@steinkuehler.net
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