Author Topic: Pi and 2801DC  (Read 1910 times)

Offline AAH

  • Hero Member
  • *****
  • Join Date: Jul 2014
  • Location: Australia
  • Posts: 591
  • Kudos: 18
  • Blinky blinky blinky
    • I love blinky lights
Pi and 2801DC
« on: July 25, 2014, 04:02:18 AM »
  I'm just wondering if anyone has connected 1 of the 2801DC15 or 2801DC30 boards that I make up to a PI using the header. I haven't trawled through all the posts but I'm hoping that I can connect 1 up over the weekend to have a play. If anyone has connected up can they confirm that the diagram I scrounged up somewhere is the correct way in which you connect up for 2801 use.
  Also what version of FPP software do I need to have on my Pi to be able to talk to the 2801 boards via the header

Thx
Alan



[attachment deleted by admin]
You can call me AAH, you can call me Al, or you can call me Alan.
http://www.hansonelectronics.com.au/wp-content/uploads/Catalogue.pdf Catalogue
http://www.hansonelectronics.com.au/

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #1 on: July 25, 2014, 09:07:52 AM »
I only tested with 2801 flex strip when adding the WS2801 output support to FPP.

You need FPP v0.3.0 to get the WS2801 support.  In the Channel Outputs screen of the UI, you'll go to the 'Other' tab and add a SPI-WS2801 output and set the start channel and number of channels desired.

The connections in the diagram are correct, that is diagram I used when developing, but I did not power the Pi from the 5V source, I left the 5V line disconnected and kept the Pi powered via the USB power.  This was mainly because I was using a 12V strip so I couldn't power the Pi off the same power source, but I also didn't want to mess with the Pi's power since I connected and disconnected the lights for testing without rebooting or power cycling the Pi.
-
Chris

Offline superman

  • Newbie
  • *
  • Join Date: Jan 2014
  • Location:
  • Posts: 31
  • Kudos: 0
Re: Pi and 2801DC
« Reply #2 on: July 28, 2014, 03:38:27 PM »
Have managed to get it going on mine tonight with one of Dave's APC748 2801toDC boards.
I have the board in as the first pixel then it was followed by a string of 18 pixel modules.
connected as follows and all works great.

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #3 on: July 28, 2014, 04:02:07 PM »
Great, thanks for the report.

Offline superman

  • Newbie
  • *
  • Join Date: Jan 2014
  • Location:
  • Posts: 31
  • Kudos: 0
Re: Pi and 2801DC
« Reply #4 on: July 29, 2014, 12:35:03 AM »
Quick question on this.

 Is the output to 2801 limited to 1 universe or as many channels as you like?
 I noticed I could actually change and save the size in "other output" for SPI-WS2801 past 510 channels.

Steve

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #5 on: July 29, 2014, 12:57:26 AM »
Quick question on this.

 Is the output to 2801 limited to 1 universe or as many channels as you like?
 I noticed I could actually change and save the size in "other output" for SPI-WS2801 past 510 channels.

Currently it is a hard-coded limit of 510 channels in the software, but this can be easily bumped up.  What sounds like a more reasonable number?  999, 1998, 3000?   I did a little bit of googling and found some people trying 500+ pixels.  We are currently driving the SPI port at 1 Mbit for the WS2801 output.  I tried going to 2 Mbit and my flex strip had issues, but I'm willing to play with the code a bit more.  It is also easy to change and test if someone wants to do some testing to see if they can run it faster.

Offline AAH

  • Hero Member
  • *****
  • Join Date: Jul 2014
  • Location: Australia
  • Posts: 591
  • Kudos: 18
  • Blinky blinky blinky
    • I love blinky lights
Re: Pi and 2801DC
« Reply #6 on: July 29, 2014, 02:41:45 AM »
I'm happy with any amount coming out of the port. 510 channels is probably enough for a lot of applications but certainly a few universes would add so much more flexibility. I can't be bothered doing the maths to work out how many pixels you can pump out at 1Mbit and still get 20 or more updates a second. I should imagine that once you go to much higher bitrates the capacitance of the cables will start screwing with the signals a fair bit. I'm all for sticking with a nice reliable bitrate like 1M and just increasing the number of pixels up to whatever can still get pumped out at 20+Hz.

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #7 on: July 29, 2014, 02:57:33 AM »
I think I'll bump it up to 1500 channels for 500 pixels.

Quick bc math says 1000000 / 8 bits / 20 hz / 3 channels per pixel = 2083 pixels theoretical max with no spacing or overhead.  500 pixels is only 25% of that so I think that should be safe.  I'll take a look at bumping this up and testing so we can get this change into the release we'd like to do next week.

Offline AAH

  • Hero Member
  • *****
  • Join Date: Jul 2014
  • Location: Australia
  • Posts: 591
  • Kudos: 18
  • Blinky blinky blinky
    • I love blinky lights
Re: Pi and 2801DC
« Reply #8 on: July 29, 2014, 04:04:32 AM »
510 pixels / 3 universes is a nice round number.
* AAH does happy dance

Offline gadgetsmith

  • Hero Member
  • *****
  • Join Date: Apr 2014
  • Location: Charlton, NY
  • Posts: 958
  • Kudos: 14
Re: Pi and 2801DC
« Reply #9 on: July 29, 2014, 04:54:49 AM »
Is 2801 the only supported pixel type right now? This could be a great solution for me for 10 pixel arches @ 50 pixels/arch.  Haven't ordered the pixels yet, but I only have WS2801 bullet pixels to test with now.

Offline AAH

  • Hero Member
  • *****
  • Join Date: Jul 2014
  • Location: Australia
  • Posts: 591
  • Kudos: 18
  • Blinky blinky blinky
    • I love blinky lights
Re: Pi and 2801DC
« Reply #10 on: July 29, 2014, 05:40:53 AM »
I believe that 2801 pixels are the only supported ones. This is mainly due to the timing requirements being so simple you could almost run 2801 pixels with a couple of toggle switches. Trying to run 2811, INK1003 and the 3 wire pixels I can't see happening as the timing for them is horrendously accurate to produce with non dedicated hardware.

Offline gadgetsmith

  • Hero Member
  • *****
  • Join Date: Apr 2014
  • Location: Charlton, NY
  • Posts: 958
  • Kudos: 14
Re: Pi and 2801DC
« Reply #11 on: July 29, 2014, 08:16:31 AM »
Thanks for the info.
(I think you may have caught on that I meant to say I have WS2811 now)

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #12 on: July 29, 2014, 09:14:33 AM »
510 pixels / 3 universes is a nice round number.
* AAH does happy dance

Makes sense, I updated my TODO list to reflect 1530 channels instead of 1500.  This will be in the new release we are targeting within the next week or so.

Offline CaptainMurdoch

  • Administrator
  • *****
  • Join Date: Sep 2013
  • Location: Washington
  • Posts: 9,014
  • Kudos: 178
Re: Pi and 2801DC
« Reply #13 on: July 29, 2014, 09:18:03 AM »
I believe that 2801 pixels are the only supported ones. This is mainly due to the timing requirements being so simple you could almost run 2801 pixels with a couple of toggle switches. Trying to run 2811, INK1003 and the 3 wire pixels I can't see happening as the timing for them is horrendously accurate to produce with non dedicated hardware.

This is correct.  The Pi will probably only ever support direct attachment of WS2801 pixels.  Once we get a BeagleBone Black FPP image, then we will look at adding support for other pixel chips because we can take advantage of the PRU's to do the pixel output since they can handle the special timing requirements.  We are currently targeting BBB support for the v1.0 release by October, but this will not probably not come with any extra features over what is available on the Raspberry Pi platform.  I don't expect to have PRU support in the initial BBB FPP release.

Offline MyKroFt

  • Administrator
  • *****
  • Join Date: Mar 2013
  • Location: NC Montana
  • Posts: 1,405
  • Kudos: 57
Re: Pi and 2801DC
« Reply #14 on: July 29, 2014, 10:50:48 AM »
Guess I better get a BBB ordered :)

Tony

 

Back to top