Easy access to RGB led from several cores

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rihorle
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Joined: Wed Aug 25, 2010 9:07 pm

Easy access to RGB led from several cores

Postby rihorle » Wed Aug 25, 2010 9:18 pm

I was wondering how one could implement an easy interface to a RGB diode connected via 3xpins to eg. core[0]. My plan is to do a Pwm function in a thread on core 0 with a channel to communicate. My question now is how does one easy send data to this thread from ANY location Core 0,1,2,3 via a simple function call eg. SetRGBled(red,green,blue); I was thinking about a Client/server via channels solution but i get stuck (channels being only point to point etc.) .. think im completely off track and need some fresh inspiration - this i prob. very trivial but multicore multithread programming is a completely new expericence to me :-)
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boeserbaer
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Joined: Fri Jan 29, 2010 4:36 pm

Postby boeserbaer » Wed Aug 25, 2010 9:49 pm

The inelegant brute force solution:

connect all the cores with channels
within the led thread select on receiving from each channel
update the leds accordingly.

Mike
rihorle
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Postby rihorle » Thu Aug 26, 2010 7:40 am

Thanks for the reply:-)
... i got it so far - but how do you do this... i allways run into the fact that channels are point to point how do you from multiple places send info to a channel?

/a
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Berni
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Postby Berni » Thu Aug 26, 2010 8:48 am

You can use a for loop cycle trough an array of channels that go to separate locations, you must use that select statement trick to make a channel not block when it has no data. This is used in the new ethernet example on the XC-2.

There should be something about this in the documentation but well it aint.
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Andy
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Postby Andy » Fri Aug 27, 2010 10:37 am

Something like this should do the trick...

Code: Select all


int consumer(chanend c_chan[], int num_chans)
{
	int i;

	while (1)
	{
		for (i=0; i < num_chans; i++)
		{
			select
			{
				case c_chan[i] :> int _ :
				{
					// Call some function
					break;
				}
				default :
				{
					// Do some default action
					break;
				}
			}
		}
	}

	return 0;
}

int foo(chanend c_chan)
{
	// Do stuff here
	// ..

	c_chan <: 1;

	return 0;
}

int main(void)
{
	chan c_chan[3];

	par
	{
		on stdcore[0] : foo(c_chan[0]);
		on stdcore[1] : foo(c_chan[1]);
		on stdcore[2] : foo(c_chan[2]);
		on stdcore[3] : consumer(c_chan, 3);
	}

	return 0;
}


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