Charles, Sorry for the delay - I had intended to follow up on this email last week. Please see below
On 6/7/2013 12:08 PM, Charles Steinkuehler wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 6/7/2013 1:31 PM, David Bagby wrote: >> Hi, >> >> We (Steve Stallings and I) would like to let you know about a >> gadget we’re expecting to bring to Wichita: The K9 SmorgasBoard. > Looks like a great board, and something folks here have been asking for. > > Just a few comments: > > In writing and testing my PRU code, the difference between using any > random GPIO pin for a task and using a direct PRU output pin is not > really that great. Yes, writing to the GPIO ports is a bit slower > than the direct output, with greater latency from the write to the > output showing up and more jitter, but when outputs are being updated > by a PRU task that is cycling every 1-10 uS, having about 100 nS > additional latency and a few 10s of nS of extra jitter isn't so bad. > For software step-gen, I don't think it matters which I/O pins you pick. The pin assignments were crafted to be able to use the PRU direct pins and still stay out of the eMMC and video area etc. Of course since all the pins can be GPIO also, we can set the board up either way - pin by pin if we need to. We tried to make the K9 very flexible (perhaps a few too many options) I'd suggest that we set one up (software wise) as GPIO for the BBB to make it easy to use your existing PRU stuff. The BBB pin assignments are arranged so that we can swap between GPIO and PRU direct via software. > My existing code is totally flexible on I/O pin assignment, you can > pick any GPIO from any of the 4 banks, and any native PRU output pin, > all by changing a hal parameter for that pin. So you can use anything > I've written to date with your board as long as you craft an > appropriate device tree overlay to get the pin muxing setup. I'm working on the DT overlay now - I hope to bring it to bring it to Wichita. Alas, I'm behind where I wanted to be by now.... sigh. > I don't have anything (yet) that talks to any SoC hardware besides the > PRU and GPIO (ie: ADC, I2C, PWM, SPI, etc), and I don't even think TI > has drivers for the encoders (at least I didn't see them in the > device-tree overlay for the counters, where I would have expected them > to show up). Some of this is easily handled by user-mode code (ie: > ADC, I2C), but HAL drivers for PWM and the encoders is currently left > as an exercise for the reader. If I get my 3D stuff going, however, > you could probably talk me into helping! :) We won't forget you said that! ;-) This is the type of situation we made the board for - the hdw will be avail on the K9, then it's "just" a matter of crafting the software. > > If you have any specific pinouts setup already, I can help with > crafting a hal_pru_generic configuration that will match up with your > board. The HAL configuration is _hopefully_ easy to understand, but > there's currently no documentation beyond the source code (it's on the > list, and will get done prior to the next SD card image release). Here's an idea: How about we target making your existing stuff run with the K9 in a configuration that would drive your printer? That sounds like a good target to aim at. I can create a BBB signal chart to make a HAL from for the K9. If you'll tell me what all you need for signal for the printer (I know the basic 4 axes S&D, but I'm uncertain what you need for other IO and analog in/out). I'll take a crack at a pin assignment that works with the default K9 firmware load, your BBB pru stuff and a matching device tree - With a bit of luck we could get your printer running from a K9 at Wichita. That's a lot of ducks to line up, but what the heck - seems worth a shot. > Keep us posted! > > - -- > Charles Steinkuehler > [email protected] > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.11 (MingW32) > Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ > > iEYEARECAAYFAlGyL64ACgkQLywbqEHdNFyrqACgrcUPVciBKIBZp0D9zwT+nHQm > bkUAoKoeWKrDJxP3qslXyo008okkYtlE > =yveN > -----END PGP SIGNATURE----- BTW - Steve will be in Wichita starting that Monday, I arrive Tues eve and will be there thru Sat (Fly back to Calif on Sun) What days will you be around? Dave ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
