3-Time-Division Display Example - NEC mPD780344 Series User Manual

18.8.2 3-time-division display example

Figure 18-17 shows the connection of a 3-time-division type 13-digit LCD panel with the display pattern shown
in Figure 18-16 with the segment signals (S0 to S38) and common signals (COM0 to COM2). The display example
is "123456.7890123," and the display data memory contents (addresses FA00H to FA26H) correspond to this.
An explanation is given here taking the example of the eighth digit from the right "6." ( ). In accordance with the
display pattern in Figure 18-16, selection and non-selection voltages must be output to pins S21 to S23 as shown
in Table 18-8 at the COM0 to COM2 common signal timings.
Table 18-8. Selection and Non-Selection Voltages (COM0 to COM2)
From this, it can be seen that ×110 must be prepared in the display data memory (address FA15H) corresponding
to S21.
Examples of the LCD drive waveforms between S21 and the common signals are shown in Figure 18-18. When
S21 is at the selection voltage at the COM1 selection timing, and S21 is at the selection voltage at the COM2 selection
timing, it can be seen that the +V
Figure 18-16. 3-Time-Division LCD Display Pattern and Electrode Connections
S
3n + 2
Remark n = 0 to 12
CHAPTER 18 LCD CONTROLLER/DRIVER
Segment
Common
COM0
COM1
COM2
S: Selection, NS: Non-selection
/–V AC square wave, which is the LCD illumination (ON) level, is generated.
LCD LCD
S
3n + 1
S
3n
User's Manual U15798EJ2V0UD
S21 S22 S23
NS S S
S S S
S S —
COM0
COM2
COM1
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