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Polarity of camera synchro signals

Pixy Software
#1

Hello,

I would like to know the polarity of the synchronization signals, because I try to have with interrupt and double buffer the frame with full resolution, and I need the polarity of HSYNC and VSYNC signals.

Thanks

#2

huh? Can you describe what you are trying to do? (more detail please)

thanks!

#3

I want to strore frames with interruption (interrupt group and DMA) that is why I need the polarity (to correctly set the interruptions).

Then I want to implement a double buffer to not read and write at the same time in a memory area. In this way I could strore a piece of image (1280 * 50), and treat at the same time in the other buffer an other piece, and continu until the end of the frame.

With interruption and DMA, I can compute a part of the frame, and store an other part.

That’s why I would like to know the polarity of the synchronisation signals. (Even if I suppose it’s ‘1’)

#4

Here’s some source that describes it — VSYNC pulses high and HSYNC pulses low.


#define CAM_PORT 		(LPC_GPIO_PORT->PIN[1])
#define CAM_VSYNC() 	(CAM_PORT&0x1000)
#define CAM_HSYNC() 	(CAM_PORT&0x800)

void vsync()
{
	int v = 0, h = 0;

	while(1)
	{
		h = 0;
		while(CAM_VSYNC()!=0);
		while(1) // vsync low
		{
			while(CAM_HSYNC()==0)
			{
				if (CAM_VSYNC()!=0)
					goto end;
			}
			while(CAM_HSYNC()!=0); //grab data
			h++;
		}
end:
		v++;
 }
}