WS2801 LED Driver Using No Library In C#

Using Arduino Project Guidance
1

I have a project in the Unity3D game engine that requires me to drive 125 WS2801 lights . I'm using the plugin Uniduino that allows me to talk to the board using standard firmata.

There is a cpp library: GitHub - adafruit/Adafruit-WS2801-Library: Arduino library for controlling strips/pixels using WS2801 driver chips

So what I'm trying to achieve is to be able to control these lights inside Unity using C#. I've been looking into this for a few days now and am pretty lost. It would have been nice if I could have created a .dll of just the library and used that but it doesn't look like there is any easy way of doing that.

Here is the product data sheet: https://www.sparkfun.com/datasheets/Components/LED/WS2801.pdf

Any help would be greatly appreciated.

2

Unity3D runs on a computer. You are running the lights from an Arduino. If I were you, I'd send serial data from the Unity3D engine to the COM port that has the Arduino connected. I'd have a sketch running on the Arduino that reads and interprets the serial commands you are sending it to control the lights.

3

Xpendable:
Unity3D runs on a computer. You are running the lights from an Arduino. If I were you, I'd send serial data from the Unity3D engine to the COM port that has the Arduino connected. I'd have a sketch running on the Arduino that reads and interprets the serial commands you are sending it to control the lights.

That certainly sounds like a plan. I've never dealt with serial ports before so this should be fun lol. I'm sure I can figure out the C# side of things quite easily, does anyone have links to docs that could help me on the arduino side? Thanks

4

Have arduino receive the 375 values (3 bytes/device), put them in an array, and then blast them out:

for (x=0; x<375; x=x+1){
SPI.transfer (dataArray[x]); // use SCK & MOSI to the WS2801
}

If set SPI clock to divide by 2, then will use 8 MHz clock and take somewhere over a 1 microsend/byte to send out. The for loop adds time, something like 12uS/transfer.
If you were to write it out as 375 discrete SPI.transfers, could send it out in about 17 clocks/byte, just over a uS/byte:
spdr = dataArray[0]; nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;
spdr = dataArray[1]; nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;
:
:
spdr = dataArray[373]; nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;
spdr = dataArray[374]; nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;nop;

I think that's the correct format for using the SPI write out register, need to look at some code I wrote for 45 bytes to do the same. The 12uS and 17 clocks came from that testing. I recall ~ 47uS to write out 45 bytes, fast enough that I could send out 45 bytes and keep up with a 20KHz trigger. Had to turn off interrupts while sending the 45 bytes out to shift registers, then turn it back on to catch the trigger.