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Valued Contributor III
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Audio CODEC trouble on DE2.

I'm trying to get Audio up on the Cyclone II starter board as a small experiment. I added a debug pin to probe the LRCLK signals, and doing so made the thing work - removing this pin will cause noise to be added to the loopback audio signal. Anyone have ideas as to what could cause this? 

 

I'm an absolute begginer to FPGAs, I managed to get RS232 and I2C up earlier. This just seems to be giving me extra trouble... 

 

In the image, VGA_B[0] is the offending pin. Changing it to other pins near the audio ones results in things still working, picking a pin far away (like GPIO_1[15]) or removing it causes the noise.
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Valued Contributor III
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Sorry, I meant DE1. I looked in the floor plan editor, and removing this pin doesn't change the routing of the other signals that much. Actually, not much seems to change at all, it just doesn't route the VGA pin. I have no constraints set up for this simple project, and all the pins are on LVTTL. I guess I'll have to probe signals on different pins with the scope and see if something changes when I change pins.

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