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DCU operating modes

Question asked by Stefan Agner on Jun 10, 2015
Latest reply on Jun 17, 2015 by Stefan Agner



Internal tests have shown different operating modes being used than documented. The Reference Manual Rev. 7 states for the field DCU_MODE in DCUx_DCU_MODE register:


DCU operating mode


DCU off (pixel clock active if enabled by I/O).
01Normal mode. Panel content controlled by layer configuration.

Test mode. DCU disables all DMA fetches and all the pixels of an enabled layer take the value in the

CLUT RAM selected by the respective LUOFFS field of control descriptor 4.

11Color Bar Generation. Panel content controlled by color bar registers.


Hence, clearing the DCU_MODE register using something like DCU_MODE & ~0x3 should turn off the DCU controller, however tests on MVF61 and MVF50 parts have shown that when clearing the DCU_MODE field, the DCU controller seems to enter the test mode. However, when using 0x2, which should be the Test mode, the display stays off (hence this seems to be the DCU off mode).


Is this a documentation error? Can somebody confirm?


Best regards,

Stefan Agner