ATMEGA3290P-20AUR Atmel, ATMEGA3290P-20AUR Datasheet - Page 239

• Manufacturer Part Number: ATMEGA3290P-20AUR
• Description: MCU AVR 32K FLASH 20MHZ 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA3290P-20AUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 69
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

23.4.2
23.4.3
8021G–AVR–03/11
Updating the LCD
Disabling the LCD
Display memory (LCDDR0, LCDDR1,...), LCD Blanking (LCDBL), Low power waveform
(LCDAB) and contrast control (LCDCCR) are latched prior to every new frame. There are no
restrictions on writing these LCD Register locations, but an LCD data update may be split
between two frames if data are latched while an update is in progress. To avoid this, an interrupt
routine can be used to update Display memory, LCD Blanking, Low power waveform, and con-
trast 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:
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 segment. 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 connected to a LCD terminal are either tri-state or output low (sink).
Assembly Code Example
C Code Example
LCD_update:
Void LCD_update(unsigned char data1, data2);
{
}
; LCD Blanking and Low power waveform are unchanged.
; Update Display memory.
sts
sts
ret
/* LCD Blanking and Low power waveform are unchanged. */
/* Update Display memory. */
LCDDR0 = data1;
LCDDR6 = data2;
1. See
LCDDR0, r20
LCDDR6, r21
”About Code Examples” on page
(1)
(1)
9.
ATmega329P/3290P
239