Rainbow-electronics Atmega169L Manuel d'utilisateur télécharger pdf (Page 219)

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ATmega169V/L

2514A–AVR–08/02

LCD Control and Status

• 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 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 Frame Complete 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 Frame Complete

Interrupt 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 76543210

LCDEN LCDAB – LCDIF LCDIE ––LCDBL LCDCRA

Read/Write R/W R/W R R/W R/W R R R/W

InitialValue00000000

1 2 ... 214 215 216 217 218 219 220 221 222 223 224 ... 316 317

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Rainbow-electronics Atmega169L Manuel d'utilisateur Page 219