VGA problem with DE2-115

Altera_Forum · ‎03-27-2014

Hello,

I have a functional VGA module working on DE0. This same VGA module also works on another board (Mercurio IV)

that has a Cyclone IV.

Today, I've tried this module on a DE2 and on a DE2-115. None of them worked properly: the three monitors just

stay black. I've made some research but could not find anything that would solve the problem. In fact, I have

no idea what the problem is.

Below are some messages that appeared and that caught my attention when I synthesized to DE2-115. None of the

messages below appear when synthesizing to DE0 and Mercurio IV,

warning: can't pack node io_module:c_io|leds_reg[5] to i/o pin

warning: node: clock_25mhz was determined to be a clock but was found without an associated clock assignment.

warning: 1 pins must meet altera requirements for 3.3-, 3.0-, and 2.5-v interfaces. for more information, refer to an 447: interfacing cyclone iv e devices with 3.3/3.0/2.5-v lvttl/lvcmos i/o systems.

info: pin clock_50 uses i/o standard 3.3-v lvttl at y2

As you can see, all of them are warnings. The pin assignments were made using the .qsf provided by Altera's site.

Any clues why the module do not work on the DE2/DE2-115?

Altera_Forum · ‎03-27-2014

Problem solved. A careful read on DE2-115 manual and I've discovered that it does not use the traditional resistor ladder but a dedicated DAC.

So for those with the same problem, read the manual and the DAC's datasheet and control the signals VGA_CLK, VGA_BLANK_N and VGA_SYNC_N.

blank <= hs and vs;

sync <= '1'; -- or maybe video_on where video_on means when pixels are in the visible area