ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 220

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

LCD Control and Status
Register B – LCDCRB
220
ATmega169/V
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 Control-
ler/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 – Res: Reserved Bit
This bit is reserved bit in the ATmega169 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 dis-
play 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 corre-
sponding 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 Inter-
rupt is enabled.
• Bits 2:1 – Res: Reserved Bits
These bits are reserved bits in the ATmega169 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
segment and common pins will be driven to ground.
• Bit 7 – LCDCS: LCD Clock Select
When this bit is written to zero, the system clock is used. When this bit is written to one,
the external asynchronous clock source is used. The asynchronous clock source is
either Timer/Counter Oscillator or external clock, depending on EXCLK in ASSR. See
“Asynchronous operation of the Timer/Counter” on page 138 for further details.
• Bit 6 – LCD2B: LCD 1/2 Bias Select
When this bit is written to zero, 1/3 bias is used. When this bit is written to one, ½ bias is
used. Refer to the LCD Manufacture for recommended bias selection.
• Bit 5:4 – LCDMUX1:0: LCD Mux Select
The LCDMUX1:0 bits determine the duty cycle. Common pins that are not used are ordi-
nary port pins. The different duty selections are shown in Table 94.
Bit
Read/Write
Initial Val-
ue
LCDCS
R/W
7
0
LCD2B
R/W
6
0
LCDMUX1
R/W
5
0
LCDMUX0
R/W
4
0
R
3
–
0
LCDPM2
R/W
2
0
LCDPM1
R/W
1
0
LCDPM0
R/W
2514P–AVR–07/06
0
0
LCDCRB