Microchip Technology DM164130-2 Data Sheet

DS41414D-page 352

 2010-2012 Microchip Technology Inc.

LCD waveforms are generated so that the net AC
voltage across the dark pixel should be maximized and
the net AC voltage across the clear pixel should be
minimized. The net DC voltage across any pixel should
be zero.
The COM signal represents the time slice for each
common, while the SEG contains the pixel data.
The pixel signal (COM-SEG) will have no DC
component and it can take only one of the two RMS
values. The higher RMS value will create a dark pixel
and a lower RMS value will create a clear pixel.
As the number of commons increases, the delta
between the two RMS values decreases. The delta
represents the maximum contrast that the display can
have.

The LCDs can be driven by two types of waveform:
Type-A and Type-B. In Type-A waveform, the phase
changes within each common type, whereas in Type-B
waveform, the phase changes on each frame
boundary. Thus, Type-A waveform maintains 0 V

DC

over a single frame, whereas Type-B waveform takes
two frames.  

 through 

 provide waveforms

for static, half-multiplex, 1/3-multiplex and 1/4-multiplex
drives for Type-A and Type-B waveforms.

If Sleep has to be executed with LCD
Sleep disabled (LCDCON<SLPEN> is
‘1’),   then care must be taken to execute
Sleep only when V

DC

 on all the pixels is

‘0’.

When the LCD clock source is F

OSC

/256,

if Sleep is executed, irrespective of the
LCDCON<SLPEN> setting, the LCD
immediately goes into Sleep. Thus, take
care to see that V

DC

 on all pixels is ‘0’

when Sleep is executed.

V

1

V

0

COM0 pin

SEG0 pin

COM0-SEG0

COM0-SEG1

SEG1 pin

V

1

V

0

V

1

V

0

V

0

V

1

-V

1

V

0

1 Frame

COM0

SEG0

SEG1

SEG2

SEG3

SEG4

SEG5

SEG6

SEG7

segment voltage

(active)

segment voltage

(inactive)