Author Topic: Possible to output a few universes over SPI on the GPIO pins?  (Read 1549 times)

Offline komby

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Possible to output a few universes over SPI on the GPIO pins?
« on: February 26, 2014, 01:23:22 PM »
I am working on a library (slowly) to add support for nRF24L01 and the RFPixelControl wireless protocol to a new dev kit called the XMOS Start Kit.  My plan is to add 4 nRF24L01 transceivers to the start kit for use as a multi universe wireless transmitter.

The start kit has a GPIO header which supports SPI and is pin compatible with the Rasberry Pi pin header. 

I havent booted my Pi yet so im a little ways away from the final solution but I do have a working transmitter on the new hardware outputting test sequences.

I am wondering if it would be able to be supported that some universes could be output on the GPIO pins to using SPI with the Rasberry Pi as the master or slave (im open).  The idea would be that the start kit board will get its data from the Pi and handle all the wireless bits.

Sound like crazy talk ????  Or does this sound like something that might just work?

link to the dev board im trying - http://www.xmos.com/zh/products/xkits/starter

Offline David Pitts

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #1 on: February 26, 2014, 01:36:37 PM »
Not crazy talk at all. Sounds good. Let me know what we can do to help.  The PI has a single SPI port with two slave select lines. Other select lines can be created using standard GPIO pins if more than two is needed. I am running the SPI port to drive FPD (Falcon Pixelnet/DMX daughter board) @ 8Mbps with only one of the slave selects. I have ran it @ 16Mbps, 32,000+ channels and it took 5% of the processors resources.

If the FPD is not on-board the SPI port is definitely free for other types of outputs and I think there is enough time to possibly share the port depending on the amount of channels the wireless board needs. We (Timon :) ) is in the process of creating an FPD that will have transceiver support for at least two different radios on a smaller FPD board (only 4 DMX/Pixelnet output rather than 12).

We are also creating a plugin architecture to support different output interfaces which may help to interface the Pi Player to what you are describing. We would love to see wireless Komby support for the Pi.


I am working on a library (slowly) to add support for nRF24L01 and the RFPixelControl wireless protocol to a new dev kit called the XMOS Start Kit.  My plan is to add 4 nRF24L01 transceivers to the start kit for use as a multi universe wireless transmitter.

The start kit has a GPIO header which supports SPI and is pin compatible with the Rasberry Pi pin header. 

I havent booted my Pi yet so im a little ways away from the final solution but I do have a working transmitter on the new hardware outputting test sequences.

I am wondering if it would be able to be supported that some universes could be output on the GPIO pins to using SPI with the Rasberry Pi as the master or slave (im open).  The idea would be that the start kit board will get its data from the Pi and handle all the wireless bits.

Sound like crazy talk ????  Or does this sound like something that might just work?

link to the dev board im trying - http://www.xmos.com/zh/products/xkits/starter
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Offline komby

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #2 on: February 26, 2014, 02:24:44 PM »
Oh Goodie!  It sounds like the Falcon Pixelnet/DMX daughter board is doing something very similar.  Its getting far more than I could handle wirelessly!  I am hoping to get 4 Universes maybe more depending on the performance.  Pretty conceptual at the moment.   

for now i'm still at the "Oh these guys are pin compatible, I should connect them and see what happens" stage :)

it may play out that its better to add a phy and ethernet and just connect with sacn

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #3 on: February 28, 2014, 08:47:54 PM »
I haven't pushed it as far as David, but I can confirm it's possible to use the SPI port for other things while FPP is running.

I put together a board w/SPI output and an RTC for use w/FPP. I was able to use OLA+lightingPi to drive 100 2801s by having FPP send e1.31 to the loopback address. CPU usage was 10-15%, most of that by OLA.

On the RPi, it may be easiest to use FPP or OLA to deal with the sacn part and interface with the API. Of course that doesn't help much with the XMOS board.

Offline komby

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #4 on: March 01, 2014, 01:47:38 AM »
I haven't pushed it as far as David, but I can confirm it's possible to use the SPI port for other things while FPP is running.

I put together a board w/SPI output and an RTC for use w/FPP. I was able to use OLA+lightingPi to drive 100 2801s by having FPP send e1.31 to the loopback address. CPU usage was 10-15%, most of that by OLA.

On the RPi, it may be easiest to use FPP or OLA to deal with the sacn part and interface with the API. Of course that doesn't help much with the XMOS board.

The xmos board seems to be a pretty straight forward c++ to C to XC port which is good.  Now I just need to find the time ;)

Offline rjchu

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #5 on: March 01, 2014, 08:24:23 PM »
This sounds exciting! Would this transmit to the "standard" RF1 Komby boards?

Thanks,

-joni-

Offline komby

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #6 on: March 01, 2014, 11:00:29 PM »
This sounds exciting! Would this transmit to the "standard" RF1 Komby boards?

Thanks,

-joni-

Yep!  That's the idea.  Just trying something a little more scalable than the arduino Ethernet transmitter.

I got a rough version of the transmit code working this week.  Lots left to do !

Here is the start kit (standalone with no pie yet).
http://youtu.be/CTPUiudS-8E

Offline rjchu

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #7 on: March 02, 2014, 10:45:33 PM »
Nice! Question for David, or others, is this compatible with the LCD displays or do they compete for pins?

Thanks,

-joni-



Yep!  That's the idea.  Just trying something a little more scalable than the arduino Ethernet transmitter.

I got a rough version of the transmit code working this week.  Lots left to do !

Here is the start kit (standalone with no pie yet).
http://youtu.be/CTPUiudS-8E

Offline David Pitts

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Re: Possible to output a few universes over SPI on the GPIO pins?
« Reply #8 on: March 02, 2014, 10:47:13 PM »
LCD uses i2c. So no they do not compete

 

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