STM32H7 VGA signal not working

MWeid.2 · ‎2020-09-07

Greetings,

today I tried generating a VGA hsync and vsync signal using PWM on my NUCLEO-H743ZI2. To be precise, I wanted to generate a 640x480@60Hz signal with the help of this page.

I analyzed the output of the PWM using my logic analyzer and thats the output for vsync and hsync:

As you can see, it's exactly as it should be. So, I have a VGA breakout connector and connected all the GNDs and the outer shield together. I also connected GND, hsync and vsync from my STM32 to it but my monitor still won't get a clear signal. I even tried reversing the polarity of the sync signals and nothing works. Using a 22 Ohm resistor also won't work.

The monitor recognizes that there is a signal but it won't let me into the menu for getting the resolution info and such, this happens on all three different monitors I tested the signal on.

Using the built-in TFT-LCD vsync and hsync of the STM32 also won't work.

I even analyzed the signal of a VGA card that I know works on this monitor using my logic analyzer and recreated the signal 1:1 using my STM32 but it still won't work.

What am I doing wrong here? There doesn't seem to be anything wrong with the signal apparently.

Thanks for you help!

Edit: Here is a poorly drawn diagram for you to better understand my connections: