AT91SAM9G10-EK Atmel, AT91SAM9G10-EK Datasheet - Page 638

• Manufacturer Part Number: AT91SAM9G10-EK
• Description: KIT DEV FOR SAM9G10 ARM
• Manufacturer: Atmel
• Type: MCUr

Specifications of AT91SAM9G10-EK

• Contents: Board, Cables, Power Supply
• Silicon Manufacturer: Atmel
• Core Architecture: AVR
• Kit Contents: Board
• Svhc: No SVHC (15-Dec-2010)
• Mcu Supported Families: AT91SAM9G10, ARM926EJ-S
• Tool / Board Applications: Microcontroller
• Rohs Compliant: Yes
• For Use With/related Products: *
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

38.5.2.6
638
AT91SAM9G10
Dithering
In STN Monochrome, only the four most significant bits of the red value are used (16 gray
shades). In STN Color, only the four most significant bits of the blue, green and red value are
used (4096 colors).
In TFT mode, all the bits in the blue, green and red values are used (32768 colors). In this mode,
there is also a common intensity bit that can be used to double the possible colors. This bit is the
least significant bit of each color component in the LCDD interface (LCDD[18], LCDD[10],
LCDD[2]). The LCDD unused bits are tied to 0 when TFT palletized configurations are used
(LCDD[17:16], LCDD[9:8], LCDD[1:0]).
The dithering block is used to generate the shades of gray or color when the LCD Controller is
used with an STN LCD Module. It uses a time-based dithering algorithm and Frame Rate Con-
trol method.
The Frame Rate Control varies the duty cycle for which a given pixel is turned on, giving the dis-
play an appearance of multiple shades. In order to reduce the flicker noise caused by turning on
and off adjacent pixels at the same time, a time-based dithering algorithm is used to vary the
pattern of adjacent pixels every frame. This algorithm is expressed in terms of Dithering Pattern
registers (DP_i) and considers not only the pixel gray level number, but also its horizontal
coordinate.
Table 38-10
Table 38-10. Dithering Duty Cycle
The duty cycles for gray levels 0 and 15 are 0 and 1, respectively.
Gray Level
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
shows the correspondences between the gray levels and the duty cycle.
Duty Cycle
1
6/7
4/5
3/4
5/7
2/3
3/5
4/7
1/2
3/7
2/5
1/3
1/4
1/5
1/7
0
Pattern Register
-
DP6_7
DP4_5
DP3_4
DP5_7
DP2_3
DP3_5
DP4_7
~DP1_2
~DP4_7
~DP3_5
~DP2_3
~DP3_4
~DP4_5
~DP6_7
-
6462A–ATARM–03-Jun-09