vol.2
Posts: 18
Joined: Tue Dec 13, 2016 5:17 pm

dpi_output_format explanation?

Sat May 18, 2019 2:58 pm

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?

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Paeryn
Posts: 2518
Joined: Wed Nov 23, 2011 1:10 am
Location: Sheffield, England

Re: dpi_output_format explanation?

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.
She who travels light — forgot something.

vol.2
Posts: 18
Joined: Tue Dec 13, 2016 5:17 pm

Re: dpi_output_format explanation?

Mon May 20, 2019 1:22 am

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. :)

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