NEC PD78F9488 Manuale Utente

CHAPTER  13   LCD  CONTROLLER/DRIVER 

 

User’s Manual  U15331EJ4V1UD

Figure 13-13 shows how a 14-digit LCD panel having the display pattern shown in Figure 13-12 is connected to the 

segment signals (S0 to S27) and the common signals (COM0 to COM3) of the 

µ

PD789489 Subseries chip.  This 

example displays the data "123456.78901234" in the LCD panel.  The contents of the display data memory 
(addresses FA00H to FA1BH) correspond to this display. 

The following description focuses on numeral "6." (   ) displayed as the ninth digit from the right.  To display "6." in 

the LCD panel, it is necessary to apply the select or deselect voltage to the S16 and S17 pins according to Table 13-6 
at the timing of the common signals COM0 to COM3; see Figure 13-12 for the relationship between the segment 
signals and LCD segments. 

 

Segment S16  S17 

Common  

 

COM0 Select 

Select 

COM1 Deselect 

Select 

COM2 Select 

Select 

COM3 Select 

Select 

 

According to Table 13-7, it is determined that the display data memory location (FA10H) that corresponds to S16 

must contain 1101. 

Figure 13-14 shows examples of LCD drive waveforms between the S16 signal and the common signals.  When 

the select voltage is applied to S16 at the timing of COM0, an alternate rectangle waveform, +V

LCD

/-V

LCD

, is generated 

to turn on the corresponding LCD segment. 

 

 

 

Remark  n = 0 to 13 

 

;;

;;

;;

;;

;

;

;;

;;

COM0

S

2n

COM1

S

2n+1

COM2

COM3