Rainbow-electronics Atmega169L Manuel d'utilisateur télécharger pdf (Page 221)

221

ATmega169V/L

2514A–AVR–08/02

• Bits 2:0 – LCDPM2:0: LCD Port Mask

The LCDPM2:0 bits determine the number of port pins to be used as segment drivers.

The different selections are shown in Table 95. Unused pins can be used as ordinary

port pins.

LCD Frame Rate Register –

LCDFRR

• Bit 7 – Res: Reserved Bit

This bit is reserved bit in the ATmega169 and will always read as zero.

• Bits 6:4 – LCDPS2:0: LCD Prescaler Select

The LCDPS2:0 bits selects tap point from a prescaler. The prescaled output can be fur-

ther divided by setting the clock divide bits (LCDCD2:0). The different selections are

shown in Table 96. Together they determine the prescaled LCD clock (clk

LCD_PS

), which

is clocking the LCD module.

Table 95. LCD Port Mask

LCDPM2 LCDPM1 LCDPM0

I/O Port in Use as

Segment Driver

Maximum Number of

Segments

0 0 0 SEG0:12 13

0 0 1 SEG0:14 15

0 1 0 SEG0:16 17

0 1 1 SEG0:18 19

1 0 0 SEG0:20 21

1 0 1 SEG0:22 23

1 1 0 SEG0:23 24

1 1 1 SEG0:24 25

Bit 76543210

– LCDPS2 LCDPS1 LCDPS0 – LCDCD2 LCDCD1 LCDCD0 LCDFRR

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

InitialValue00000000

Table 96. LCD Prescaler Select

LCDPS2 LCDPS1 LCDPS0

Output

from

Prescaler

clk

LCD

Applied Prescaled LCD Clock

Frequency when LCDCD2:0 = 0,

Duty = 1/4, and Frame Rate = 64 Hz

000clk

LCD

/16 8.1 kHz

001clk

LCD

/64 33 kHz

010clk

LCD

/128 66 kHz

011clk

LCD

/256 130 kHz

100clk

LCD

/512 260 kHz

101clk

LCD

/1024 520 kHz

110clk

LCD

/2048 1 MHz

111clk

LCD

/4096 2 MHz

1 2 ... 216 217 218 219 220 221 222 223 224 225 226 ... 316 317

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Rainbow-electronics Atmega169L Manuel d'utilisateur Page 221

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