Datasheet

RL78/L12 CHAPTER 14 LCD CONTROLLER/DRIVER

R01UH0330EJ0200 Rev.2.00 636

Dec 13, 2013

14.9 Common and Segment Signals

14.9.1 Normal liquid crystal waveform

Each pixel of the LCD panel turns on when the potential difference between the corresponding common and segment

signals becomes higher than a specific voltage (LCD drive voltage, V

LCD). The pixels turn off when the potential difference

becomes lower than V

LCD.

Applying DC voltage to the common and segment signals of an LCD panel causes deterioration. To avoid this problem,

this LCD panel is driven by AC voltage.

(1) Common signals

Each common signal is selected sequentially according to a specified number of time slices at the timing listed in

Table 14-13. In the static display mode, the same signal is output to COM0 to COM3.

In the two-time-slice mode, leave the COM2 and COM3 pins open. In the three-time-slice mode, leave the COM3

pin open.

Use the COM4 to COM7 pins other than in the eight-time-slice mode as open or segment pins.

Table 14-13. COM Signals

COM0 COM1 COM2 COM3

Static display mode

Two-time-slice mode Open Open

OpenThree-time-slice mode

Four-time-slice mode

COM Signal

Number of

Time Slices

Eight-time-slice mode

COM4 COM5 COM6 COM7

Note

Note Use the pins as open or segment pins.