SimonC
8/9/2012 9:55:28 AM
User Rank Beginner
Re: VGA and LEDs
I'm trying to configure the registers of the AD9980 using the I2C bus and my FPGA. I'm writing on the SDA and the SCL pins with a SCL-frequency of 100 kHz. However it doesn't seem to work. I'm trying but I don't think I wrote in the registers.
Anyone has some experience with this?
Any help would be greatly appreciated,
Simon
SimonC
8/8/2012 10:17:40 AM
User Rank Beginner
Re: VGA and LEDs
I think there is a problem with the AD9980 (see http://www.analog.com/static/imported-files/data_sheets/AD9980.pdf) because when I switch the resolution of a computer on 800 x 600 or on 1680 x 1050 , both at 60 Hz and feed this in the AD9980, the AD9980 keeps on outputting a dataclock with a period of 20 ns to the FPGA. While this period should be 6.79 ns for the 1680 x 1050 @ 60 Hz and 25 ns at 800 X 600 @ 60 Hz.
Is this normal?
SimonC
8/7/2012 12:44:34 PM
User Rank Beginner
Re: VGA and LEDs
I think I still have a problem with the exact timing. I have send you the code and the testbench.
Re: VGA and LEDs
if you get stuck send me a email with your code etc
SimonC
8/6/2012 5:31:09 PM
User Rank Beginner
Re: VGA and LEDs
Thanks, I'll keep on trying ;)
SimonC
8/6/2012 11:32:46 AM
User Rank Beginner
VGA and LEDs
Hi,
I 'm trying another home-made exercice ;) . I have connected a VGA input (another PC) to my FPGA and i'm trying to light some LEDs depending on the color of a pixel somewhere in the middle of a frame. I am using 800 X 600 @ 72 Hz resolution. I have read about VGA and I know I think I need 1040 pixels on a row and 666 pixelrows on a frame. (The pixelfrequency is 50 MHz. )
The VGA input on my FPGA delivers 8 bit for blue, 8 bit for red and 8 bit for green. a horizontal and vertical synchronisation signal. However when I make a colored frame (for example in 'paint' opening a black screen) , input this to VGA and assign for example the blue 8 bit vector on a specific pixel of the frame to the 8 LEDs, I get always '0' on my LEDs, even when I input a white or a blue frame.
I use the following principle: the first data that enters is a vertical blanc signal, followed by a horizontal blanc signal, followed by a row of screen-pixels, followed by a horizontal blanc signal, followed by a horizontal synchronisation signal (end of row 1). Then again a horizontal blanc signal, a row of screen pixels, a horizontal blanc signal and a horizontal sync (end of row 2),... etc. Every frame is concluded by a vertical blanc signal and a vertical synchronisation.
The specific timings for the signals, I found on this website: http://tinyvga.com/vga-timing/800x600@72Hz
Is this the correct way to do it? Or should you start with a synchronisation signal? Or start with the row of screen-pixels?
Thanks in advance,
Simon
SimonC
7/31/2012 5:22:37 AM
User Rank Beginner
Re: RS 232 and LEDS
I'll certainly follow up that one ;)
Made some code today for interfacing the PS/2 keyboard to some LEDs, tested it out and it works. Yeah!! ;)
There is one strange thing though, I have noticed that a few LEDs that are 'low', blink up for a very short time in between two characters I type with the keyboard.
SimonC
7/31/2012 5:11:37 AM
User Rank Beginner
Re: Communications
Totally agreed ;)
Re: RS 232 and LEDS
Glad it works ;) I will be blogging about it soon as part of vga controller I have been working on.
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