PXD20RM Datasheet, PDF (414/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Mode
Normal
PDI normal
PDI slave
Table 11-58. List of DCU3 operating modes
DCU_MODE[1:0]
01
01
01
PDI_EN
0
1
0
Description
DCU3 blends layers and displays result on TFT LCD panel.
As normal mode, except that the panel timing is defined by the input on
the PDI interface, and the background color is replaced by the content
provided on the PDI interface.
The DCU3 synchronizes its timing to an external signal when
PDI_SLAVE_MODE is enabled.
The DCU_MODE, PDI_EN and PDI_SLAVE_MODE control bits are in the DCU_MODE register. The
DCU3 has an interface enable bit for the TFT LCD panel interface called RASTER_EN, also in the
DCU_MODE register. When RASTER_EN is 0 the raster scanning of pixels to the panel is disabled but
the pixel clock continues to run as long if enabled on the I/O pin.
Color bar mode is intended for testing the interface between the DCU3 and the TFT LCD panel. In this
mode, the panel is divided into eight vertical strips of equal width, and the strips display a single color
whose RGB value is specified in the COLBAR_1 to COLBAR_8 registers. At reset, the colors are set to
black, blue, cyan, green, yellow, red, magenta, and white, where positive logic for the RGB values is
assumed. The mode can be used to verify correct connection of the interface to the DCU3 and correct
timing configuration of the interface. In this mode, any layer configuration settings are ignored.
In Normal mode, the DCU3 operates according to the timings specified in Section 11.4.2, TFT LCD panel
configuration and displays graphics according to the configuration of its layers. The BGND register sets
the RGB color of the background shown when no other layers are present. This background color is
included in the layer blending process but, since it is always the background, it does not include any layer
blending settings.
In PDI normal mode, the DCU3 adopts the timing provided on the PDI interface and replaces the
background color by the pixel data coming from the PDI interface. The timing values set in the DCU3 are
ignored in this mode, and the pixel clock and synchronization signals are taken from the PDI interface and
passed to the TFT LCD panel. The content of the panel is a combination of the incoming pixel stream and
layers generated by the DCU3.
PDI slave mode allows the DCU3 to synchronize with the external timing signals on the PDI input.
11.4.4 Layer configuration and blending
Users control the graphical content of the TFT panel by manipulating the configuration of elements in the
DCU3 called layers. Each layer has a control descriptor that defines the size, position, memory encoding,
blending, and memory location of the graphic to be displayed. The DCU3 provides 16 independent layers
that are identical except that they have a fixed priority with respect to each other, and this affects how
individual pixels are blended when layers overlap. The blending setting on each layer allows the pixels on
that layer to be opaque, partially transparent, or fully transparent, which allows them to combine with
pixels on other layers that they overlap.
11-80
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor