RA8875 has ridiculous registers
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The RA8875 is a controller for an 800x480 display I am using in a project. You can rotate the screen via setting some registers. There is no option to rotate 90 degrees, only 270, leaving the X axis, and thus text and bitmaps mirrored. Whoever designed this should be forced to use it.
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Can't you just rotate it 3 times to get 90 degrees? Inelegant, but I must be missing something.
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Can't you just rotate it 3 times to get 90 degrees? Inelegant, but I must be missing something.
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The fox knows many things, but the hedgehog knows one big thing.It's not quite 5am and my spatial reasoning may not be entirely on point right now. Basically when I rotate it, it goes 90 degrees with the X axis inverted. You cannot rotate it 3 times nor flip the X axis because they only use 2 bits to store the rotation. These are the directions you can set the memory write order: LRTD RLTD TDLR DTLR (T=Top, R=Right, D=Down, L=Left)
Real programmers use butterflies
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The RA8875 is a controller for an 800x480 display I am using in a project. You can rotate the screen via setting some registers. There is no option to rotate 90 degrees, only 270, leaving the X axis, and thus text and bitmaps mirrored. Whoever designed this should be forced to use it.
Real programmers use butterflies
Because you can mirror the x axis yourself reading the lines backwards.
GCS d--(d-) s-/++ a C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- r+++ y+++* Weapons extension: ma- k++ F+2 X
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The RA8875 is a controller for an 800x480 display I am using in a project. You can rotate the screen via setting some registers. There is no option to rotate 90 degrees, only 270, leaving the X axis, and thus text and bitmaps mirrored. Whoever designed this should be forced to use it.
Real programmers use butterflies
"Rotate" doesn't exist -- there are only flips, on three axes. :-D Odd that they provide only two bits when you need three.
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"Rotate" doesn't exist -- there are only flips, on three axes. :-D Odd that they provide only two bits when you need three.
Call it what you want. You know what I was talking about so I did my part. Prescriptivism is annoying.
Real programmers use butterflies
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Because you can mirror the x axis yourself reading the lines backwards.
GCS d--(d-) s-/++ a C++++ U+++ P- L+@ E-- W++ N+ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t+ 5? X R+++ tv-- b+(+++) DI+++ D++ G e++ h--- r+++ y+++* Weapons extension: ma- k++ F+2 X
Yeah, no. Because then you can't send bitmap data using DMA, and you need to generate a lot more bus traffic. The device should have been designed correctly.
Real programmers use butterflies
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The RA8875 is a controller for an 800x480 display I am using in a project. You can rotate the screen via setting some registers. There is no option to rotate 90 degrees, only 270, leaving the X axis, and thus text and bitmaps mirrored. Whoever designed this should be forced to use it.
Real programmers use butterflies
Could you do the rotation and then use the horizontal and vertical scan direction registers to mirror the display (and get an extra 180 degrees of rotation)?
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Could you do the rotation and then use the horizontal and vertical scan direction registers to mirror the display (and get an extra 180 degrees of rotation)?
It doesn't have registers for mirroring aside from the two bits it uses, and I need three.
Real programmers use butterflies
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It doesn't have registers for mirroring aside from the two bits it uses, and I need three.
Real programmers use butterflies
Register 20H instead of 40H/45H? Or is that the wrong controller I am looking at? It might be something completely different or not do what you need. I agree, it does need three bits to get all of the rotations/mirrors that are possible and they have a spare bit, so why didn't they just give all eight options?
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Register 20H instead of 40H/45H? Or is that the wrong controller I am looking at? It might be something completely different or not do what you need. I agree, it does need three bits to get all of the rotations/mirrors that are possible and they have a spare bit, so why didn't they just give all eight options?
Fueled By Decaff wrote:
Register 20H instead of 40H/45H?
Nice catch! I guess my eyes are glazing over it after poring over it for a day while writing a driver for it. I'll see if it works. I don't know why they didn't use 3 bits. It's just weird.
Real programmers use butterflies
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Register 20H instead of 40H/45H? Or is that the wrong controller I am looking at? It might be something completely different or not do what you need. I agree, it does need three bits to get all of the rotations/mirrors that are possible and they have a spare bit, so why didn't they just give all eight options?
You're my friggin hero today. :thumbsup::thumbsup::thumbsup: It worked. It's weird reversing both reads and writes, but it worked. Woo! Thank you so much!
Real programmers use butterflies
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It's not quite 5am and my spatial reasoning may not be entirely on point right now. Basically when I rotate it, it goes 90 degrees with the X axis inverted. You cannot rotate it 3 times nor flip the X axis because they only use 2 bits to store the rotation. These are the directions you can set the memory write order: LRTD RLTD TDLR DTLR (T=Top, R=Right, D=Down, L=Left)
Real programmers use butterflies
I'm missing the TLDR option ;P
Wrong is evil and must be defeated. - Jeff Ello
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Fueled By Decaff wrote:
Register 20H instead of 40H/45H?
Nice catch! I guess my eyes are glazing over it after poring over it for a day while writing a driver for it. I'll see if it works. I don't know why they didn't use 3 bits. It's just weird.
Real programmers use butterflies
Probably their use case is flipping the image for projectors. [how do i flip the projector image upside down](https://www.justprojectors.com.au/blog/flipping\_the\_projected\_image\_upside\_down\_for\_ceiling\_installation.htm)
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Probably their use case is flipping the image for projectors. [how do i flip the projector image upside down](https://www.justprojectors.com.au/blog/flipping\_the\_projected\_image\_upside\_down\_for\_ceiling\_installation.htm)
Usually these IoT display controllers allow you to rotate any direction due to the screen orientation being unknown in advance. In any case, thanks to FueledByDecaf I worked it out by adjusting both the write order and the scan direction both.
Real programmers use butterflies
