LCD-TFT Controller (LTDC)
RM0090
488/1731
DocID018909 Rev 11
Color Frame Buffer Address
Every Layer has a start address for the color frame buffer configured through the
LTDC_LxCFBAR
register.
When a layer is enabled, the data is fetched from the Color Frame Buffer.
Color Frame Buffer Length
Every layer has a total line length setting for the color frame buffer in bytes and a number of
lines in the frame buffer configurable in the
LTDC_LxCFBLR
and
LTDC_LxCFBLNR
register respectively.
The line length and the number of lines settings are used to stop the prefetching of data to
the layer FIFO at the end of the frame buffer.
•
If it is set to less bytes than required, a FIFO underrun interrupt is generated if it has
been previously enabled.
•
If it is set to more bytes than actually required, the useless data read from the FIFO is
discarded. The useless data is not displayed.
Color Frame Buffer Pitch
Every layer has a configurable pitch for the color frame buffer, which is the distance between
the start of one line and the beginning of the next line in bytes. It is configured through the
LTDC_LxCFBLR
register.
Layer Blending
The blending is always active and the two layers can be blended following the blending
factors configured through the
LTDC_LxBFCR
register.
The blending order is fixed and it is bottom up. If two layers are enabled, first the Layer1 is
blended with the Background color, then the Layer2 is blended with the result of blended
color of Layer1 and the background. Refer to
Figure 84. Blending two layers with background
069
/D\HU
/D\HU
%*
/D\HU
/D\HU%*
/D\HU
/D\HU%*