239
2552K–AVR–04/11
ATmega329/3290/649/6490
23.4
Register Description
23.4.1
LCDCRA – LCD Control and Status Register A
Bit 7 – LCDEN: LCD Enable
Writing this bit to one enables the LCD Controller/Driver. By writing it to zero, the LCD is turned
off immediately. Turning the LCD Controller/Driver off while driving a display, enables ordinary
port function, and DC voltage can be applied to the display if ports are configured as output. It is
recommended to drive output to ground if the LCD Controller/Driver is disabled to discharge the
display.
Bit 6 – LCDAB: LCD Low Power Waveform
When LCDAB is written logic zero, the default waveform is output on the LCD pins. When
LCDAB is written logic one, the Low Power Waveform is output on the LCD pins. If this bit is
modified during display operation the change takes place at the beginning of a new frame.
Bit 5 – Reserved Bit
This bit is reserved bit in the ATmega329/3290/649/6490 and will always read as zero.
Bit 4 – LCDIF: LCD Interrupt Flag
This bit is set by hardware at the beginning of a new frame, at the same time as the display data
is updated. The LCD Start of Frame Interrupt is executed if the LCDIE bit and the I-bit in SREG
are set. LCDIF is cleared by hardware when executing the corresponding Interrupt Handling
Vector. Alternatively, writing a logical one to the flag clears LCDIF. Beware that if doing a Read-
Modify-Write on LCDCRA, a pending interrupt can be disabled. If Low Power Waveform is
selected the Interrupt Flag is set every second frame.
Bit 3 – LCDIE: LCD Interrupt Enable
When this bit is written to one and the I-bit in SREG is set, the LCD Start of Frame Interrupt is
enabled.
Bits 2:1 – Reserved Bits
These bits are reserved bits in the ATmega329/3290/649/6490 and will always read as zero.
Bit 0 – LCDBL: LCD Blanking
When this bit is written to one, the display will be blanked after completion of a frame. All seg-
ment and common pins will be driven to ground.
23.4.2
LCDCRB – LCD Control and Status Register B
Note:
Bit 3, LCDPM3 is only available in ATmega3290/6490.
Bit
765
4321
0
LCDEN
LCDAB
–
LCDIF
LCDIE
–
LCDBL
LCDCRA
Read/Write
R/W
R
R/W
R
R/W
Initial Value
000
0000
0
Bit
7
6
5
4
3
2
1
0
LCDCS
LCD2B
LCDMUX1
LCDMUX0
LCDPM3
LCDPM2
LCDPM1
LCDPM0
LCDCRB
Read/Write
R/W
Initial Val-
ue
0
00