LPC1788 LCD and DMA issue

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LPC1788 LCD and DMA issue

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by monnoliv on Thu Nov 10 03:34:03 MST 2011
Hello,
I'm using the FDI dev kit with LPC1788 and a 640x480 LCD. In order to speed up LCD drawing, I'm using memory to memory DMA transfert with linked list. The purpose is to do 2D block transfert from a area of a frame buffer to another area of the frame buffer (or to another frame buffer).
The code run well for small area (typically 12x12 pixels or 2x30pixels or 40x2 pixels). But when the area to move is bigger, it seems that the DMA is interrupted after a certain amount of transfert. This problem is only visible when linked lists are used, I can transfert a large amount (typ: 4000x16 bits) of linear data without linked lists without problem.
I see on the screen that the DMA tansfert is interrupted because if I move a block of (say) 40x40 pixels on the screen (display, erase, increment, display,...) It remains some pixels that are not "cleared".
I think that this is due to a conflict between DMA and LCD controler. Is this possible? Do I stop refreshing LCD during DMA transfert?
Regards,
Olivier
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abderrezak
Contributor III

Did you solve your problem. I want to try same thing as you (developing a graphical library with 5 buffer) but I can' use DMA. Can you attach a sample code. I am using the LPCOpen.

Thank you

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