flickerfixer
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niklasekstrom
Try finding top-left corner of display window from PIXELSW pin
Denise has an output pin PIXELSW that is supposed to indicate if a pixel has the background color or not. It might be possible to use this pin in some clever way to find the top-left corner of the display window (DIWSTRT), which could be used to remove overscan and only output the pixels in the display window. Probably one has to make additional assumptions about the size of the display window for this to work, which may only work in certain circumstances. Experiment!
I did a small experiment this evening and the PIXELSW pin does what the documentation says, i.e. it is active if a pixel has the background color.
@polluks HDMI sounds great, I would like it very much myself. The only reason I'm using VGA is because it is simple and because there's a VGA connector on the DE10-Lite FPGA dev board.
You don't happen to have a suggestion for a good and easy to use HDMI serializer chip?
HDMI serializer chips are only sold to HDMI Adopters (joining fee $5,000). However, it's relatively straightforward to serialize video data on an FPGA and then output it directly to an HDMI connector (or more robustly via a buffer chip such as the TI TMDS141 - which doesn't require joining the HDMI forum).
I have previously worked on an open-source HDMI design in Verilog for Xilinx FPGAs: https://github.com/projf/display_controller
It should be relatively painless to adapt to Altera.
Alternatively you can generate DVI (which should be compatible with HDMI) using the TFP410: http://www.ti.com/product/TFP410 - though since this is DVI you don't get audio.
Hi @WillGreen. Thanks for the information! The TFP410 sounds quite interesting.
Regarding serializing HDMI signals on the FPGA, isn't it the case that the frequencies become very high? For example, I want to output 1280x1024@60Hz which has a pixel clock of 108 MHz, wouldn't that mean that the HDMI frequency is 10 times that, i.e. over 1 GHz, which a 10M02 FPGA certainly can't handle ?
What do you think of buying a chip such as Analog Devices ADV7513 from AliExpress? I haven't tried buying anything from there yet, and it seems a bit shady with what you wrote about having to be an HDMI adopter, but since it's only for personal use I wouldn't expect there to be any bad consequences, if the chips are actually legitimate. At least the prices seems quite reasonable.