Datasheet

231
ATmega169A/PA/329A/PA/649A/P/3290A/PA/6490A/P [DATASHEET]
8284E–AVR–02/2013
ress. To avoid this, an interrupt routine can be used to update Display memory, LCD Blanking, Low power
waveform, and contrast control, just after data are latched.
In the example below we assume SEG10 and COM1 and SEG4 in COM0 are the only segments changed from
frame to frame. Data are stored in r20 and r21 for simplicity
Note: 1. See ”About code examples” on page 11.
24.4.3 Disabling the LCD
In some application it may be necessary to disable the LCD. This is the case if the MCU enters Power-down mode
where no clock source is present.
The LCD should be completely discharged before being disabled. No DC voltage should be left across any seg-
ment. The best way to achieve this is to use the LCD Blanking feature that drives all segment pins and common
pins to GND.
When the LCD is disabled, port function is activated again. Therefore, the user must check that port pins con-
nected to a LCD terminal are either tri-state or output low (sink).
Assembly code example
(1)
LCD_update:
; LCD Blanking and Low power waveform are unchanged.
; Update Display memory.
sts LCDDR0, r20
sts LCDDR6, r21
ret
C code example
(1)
Void LCD_update(unsigned char data1, data2);
{
/* LCD Blanking and Low power waveform are unchanged. */
/* Update Display memory. */
LCDDR0 = data1;
LCDDR6 = data2;
}