Atmel SAM4L Xplained Pro Evaluation Kit Atmel ATSAM4L-XPRO ATSAM4L-XPRO 数据表

42023E–SAM–07/2013

When LCD controller is disabled all segment and common terminals are driven to GND, dis-
charging the LCD in order to avoid DC voltage across the segments and a slowly fading image.
Data in the display memory is preserved.

In order to restart correctly, it is preferrable to disable all functions (blinking, FCx,...) before dis-
abling LCD controller.

To reduce toggle activity and hence power consumption, write a zero to the Waveform Mode
(CFG.WMOD) to enable the low power waveform mode (the LCD glass must support this
mode). The low power waveform period is then twice the standard waveform period, in both
modes DC voltage is null.

To select the standard waveform, write a one to the CFG.WMOD bit. This bit shall not be modi-
fied when LCDCA is enabled.

Figure 39-8. Waveform Modes (Three Common Lines)

The Prescaler field (PRESC) in Timing register (TIM) selects a tap point from a ripple counter.
The ripple counter output can be further divided by setting the Clock Divider (CLKDIV[2:0]).

V

LCD

2/3 V

LCD

1/3 V

LCD

GND

GND

V

LCD

2/3 V

LCD

1/3 V

LCD

GND

V

LCD

2/3 V

LCD

1/3 V

LCD

-1/3 V

LCD

-2/3 V

LCD

-V

LCD

Frame 1

Frame 2

Standard waveform

V

Threshold

-V

Threshold

SEG0-COM0

COM0

SEG0

V

LCD

2/3 V

LCD

1/3 V

LCD

GND

GND

V

LCD

2/3 V

LCD

1/3 V

LCD

GND

V

LCD

2/3 V

LCD

1/3 V

LCD

-1/3 V

LCD

-2/3 V

LCD

-V

LCD

Frame 1

Low power waveform

V

Threshold

-V

Threshold

SEG0-COM0

COM0

SEG0

T = 20ms

T = 40ms

LCD Prescaler Selection

0

CLK_LCD / 8

1

CLK_LCD

 

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