To play with FPGA brings a lot of fun and for me it’s only a hobby to learn something new. But without any goal, it makes no sense to learn that stuff. That’s why, I decided to build my own oscilloscope. Ok, not now and not within the next weeks, but as a long-term goal.
For that I need a display to show the information. First I try to display information on a monitor via VGA. It seems to be a relatively easy protocol and next I can switch to parallel driven LCD.
Unfortunately my DE0-Nano does not contain a VGA-output as many other evaluation-boards, but it should not be so hard to connect a VGA-connector to some of the free IO-pins of the board. After studying the pinout of a VGA-connector I realised, that only 6 GPIO-pins of my board need to be used. One for each color (red, green and blue), one for HSYNC, one for VSYNC and one for GND, connected to all GND-signals of the VGA-connector.
The VGA-connector itself I salvaged from an old projector with a defect light-bulb. This very old projector was not used anymore for several years and I didn’t want to wait for the delivery of a single VGA-connector.
Because the connector can not be used on a breadboard, a small adapter-board was necessary. I used Eagle CAD to layout the board and had to implement the connector as a new element first, because I could not find the right layout in the database.
I wrote another article about how to layout, print, develop and etch the board, so you can see what to do for that. At the end it looks like that. It’s only a quick prototype, so now solder mask or tenting was used here.
The adaptor can easily connected to the board via dupont cables (breadboard-wires). The pins 5-8 and 10 of the VGA-connector are connetcted, so GND of the board only need to be connected to one of these.