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sdsteam
60 Posts |
 Posted - 16 Jan 2007 : 00:45:28
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hi,
We are using Bitsy-X in our application, we are facing the problem with LCD wherein it is flickering at random intervals of time. It is found that whenever we are doing CF write operations the LCD Screen is getting flickered. Thought that it is due to CF generated EMI, but when we tested the same CF write operation in the Bitsy-X development board with periodic intervals of writting data onto the CF, the Same LCD flickering is happening in the same intervals (The operating system used is Linux). Kindly guide us to proceed further in providing the solution for this. Our product launch is getting effected due to this LCD flickering.
Thanks & Regards
Kamakshi K |
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rwhaley
628 Posts |
Posted - 17 Jan 2007 : 15:05:16
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The most common cause for panel flicker when using PXA255 processor on chip panel hardware is memory starvation of the framebuffer caused by the CF/PCMCIA bus hogging the address and data lines during transfers. This matches the symptoms you report.
In panel configurations and kernels made by ADS this is generally not a problem. Because we are careful to make sure that the CF/PCMCIA bus timing is fast enough and the pixclock rate for the panel is slow enough that flicker will not occur. When using an ADS kernel these timing changes are easy to make through kernel command line and framebuffer register setting without rebuilding the kernel.
We believe that you are not using an ADS kernel. Because of this you will probably need to make these changes in the kernel source code. We don't have your kernel source code so we cannot be sure, but the most likely places you will need to make changes are in the drivers/video/pxafb.* files and in the drivers/pcmcia/pxa/adsbitsyx.c file or arch/arm/mach-pxa/adsbitsyx.c. Generally speaking, flicker can be eliminated by slowing down the framebuffer timing and/or speeding up the CF/PCMCIA timing.
If you are using our kernel we should be able to help reduce flicker, but we will need to see the register.txt file you are using and we also need to know which version of the kernel you are running and what model panel you are using. |
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akidder
1519 Posts |
Posted - 17 Jan 2007 : 16:08:39
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If you can email us the model of the LCD you are using, we may be able to suggest timings that would work for your application, if we have configured that display for the PXA255 before. It will also help if you can give us the values you are using for CompactFlash bus and display timings (PXA255 registers LCCR0-3 and MCATT1, MCIO1 and MCMEM1).
For further reading: Display topic index, display flicker. |
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LCD Flickering in Bitsy Development board
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