dbird
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Joined: Fri Jun 22, 2018 6:23 pm

Re-order the DPI pins

Fri Jun 22, 2018 6:39 pm

I'm troubleshooting a new PCB and am in need of some help! I understand how to change the order of RGB for the DPI. I want to know if there's a way to re-order the individual bits. For example, instead of R0-R7 it would be R7-R0. I have a board that uses the compute module and in testing I've discovered that each of the colors' MSB and LSB are swapped from what I need. So the I've got R0-R7, G0-G7, and B0-B7 coming from the board instead of the R7-R0, G7-G0 and B7-B0 that is the pinout on the screen. An image shows up on the screen, but the color is all wrong. I've been searching for an answer, but I haven't found any more information on the way the DPI is configured than the documentation on the rpi website. The dtb file only sets the GPIO to the Alt function. It doesn't define the order to the best of my knowledge. Config.txt looks to only change the order of the colors not the order with any color.

Image

Thanks,
David

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DougieLawson
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Re: Re-order the DPI pins

Sat Jun 23, 2018 8:15 am

You may be able to build a new version of the vga666 overlay.

This is the current source for it.
https://github.com/raspberrypi/linux/bl ... verlay.dts
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Re: Re-order the DPI pins

Tue Jun 26, 2018 9:39 am

There is no way to amend the order of the bits in the DPI interface, nor move them to GPIOs other than those listed in that table.
As documented in https://www.raspberrypi.org/documentati ... /README.md, you can swap the order that the red, green, and blue are ordered, but not the bit order.
Sorry, you're going to need to respin your PCB.
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Slackware
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Re: Re-order the DPI pins

Tue Jun 26, 2018 1:24 pm

maybe you can use a parallel to serial shift register chip to spit them out in the order you want. After all you can input any line in to get the order you want out.

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