Raspberry Pi Forums

Hello, I have read all of this Docs:
https://www.raspberrypi.org/documentati ... /README.md

and I wonder if someone can help me understand what output format does?

I have a config.txt designed for a GPIO to component video peripheral, and it uses the parameter dpi_output_format=519. Is this specific to the 8 bit color output? Can someone explain how the number 519 was calculated? Is it hex?

519 is the decimal value, converting it to binary that is bits 0,1,2 & 9 set, looking at the format that means mode 7 (bits 0 to 3) which is 24 bit colour RGB888 and bit 9 means inverted pixel clock (data changes on falling edge, stable on rising). All other bits 0 so hsync, vsync & oe polarity are the default HDMI polarities and their phases are positive edge.

Not sure how rgb order is handled as that page says bits 4 to 7 hold that and your value has 0 (none set) but the rgb orders listed are 1 to 4.

Paeryn wrote: ↑

Sat May 18, 2019 9:03 pm

519 is the decimal value, converting it to binary that is bits 0,1,2 & 9 set, looking at the format that means mode 7 (bits 0 to 3) which is 24 bit colour RGB888 and bit 9 means inverted pixel clock (data changes on falling edge, stable on rising). All other bits 0 so hsync, vsync & oe polarity are the default HDMI polarities and their phases are positive edge.

Not sure how rgb order is handled as that page says bits 4 to 7 hold that and your value has 0 (none set) but the rgb orders listed are 1 to 4.

Thanks! I'm going to have to do a little homework, but I think you gave me everything I need to figure out what's going on.

Paeryn wrote: ↑

Sat May 18, 2019 9:03 pm

Not sure how rgb order is handled as that page says bits 4 to 7 hold that and your value has 0 (none set) but the rgb orders listed are 1 to 4.

Yeah me neither. I'm setting the format at the moment for my screen and the docs gives me some doubt. (google brought me here)

So indeed, bit 4 till 7 hold the RGB order. Now if we look at the example at the bottom of the page, it gives as format example: `dpi_output_format=0x6f005`
Now from this we can see that bits 4 till 7 are zero, hence `rgb_order` is equal to `0` and `0` is no option in the table. So either the example or the table is wrong (or I am missing something)
Also bit 15 is set but isn't used in the format.