PCF8566 查看數據表（PDF） - Philips Electronics

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PCF8566

Universal LCD driver for low multiplex rates

Philips Electronics 

Philips Semiconductors

Universal LCD driver for low multiplex

rates

Product specification

PCF8566

6.16 Output bank selector

This selects one of the four bits per display RAM address

for transfer to the display latch. The actual bit chosen

depends on the particular LCD drive mode in operation

and on the instant in the multiplex sequence. In 1 : 4

multiplex, all RAM addresses of bit 0 are the first to be

selected, these are followed by the contents of bit 1, bit 2

and then bit 3. Similarly in 1 : 3 multiplex, bits 0, 1 and 2

are selected sequentially. In 1 : 2 multiplex, bits 0 then 1

are selected and, in the static mode, bit 0 is selected.

The PCF8566 includes a RAM bank switching feature in

the static and 1 : 2 multiplex drive modes. In the static

drive mode, the BANK SELECT command may request

the contents of bit 2 to be selected for display instead of

bit 0 contents. In the 1 : 2 drive mode, the contents of

bits 2 and 3 may be selected instead of bits 0 and 1.

This gives the provision for preparing display information

in an alternative bank and to be able to switch to it once it

is assembled.

6.17 Input bank selector

The input bank selector loads display data into the display

RAM according to the selected LCD drive configuration.

Display data can be loaded in bit 2 in static drive mode or

in bits 2 and 3 in 1 : 2 drive mode by using the BANK

SELECT command. The input bank selector functions

independently of the output bank selector.

6.18 Blinker

The display blinking capabilities of the PCF8566 are very

versatile. The whole display can be blinked at frequencies

selected by the BLINK command. The blinking frequencies

are integer multiples of the clock frequency; the ratios

between the clock and blinking frequencies depend on the

mode in which the device is operating, as shown in

Table 4.

An additional feature is for an arbitrary selection of LCD

segments to be blinked. This applies to the static and 1 : 2

LCD drive modes and can be implemented without any

communication overheads. By means of the output bank

selector, the displayed RAM banks are exchanged with

alternate RAM banks at the blinking frequency. This mode

can also be specified by the BLINK command.

In the 1 : 3 and 1 : 4 multiplex modes, where no alternate

RAM bank is available, groups of LCD segments can be

blinked by selectively changing the display RAM data at

fixed time intervals.

If the entire display is to be blinked at a frequency other

than the nominal blinking frequency, this can be effectively

performed by resetting and setting the display enable bit E

at the required rate using the MODE SET command.

Table 4 Blinking frequencies

BLINKING MODE

Off

2 Hz

1 Hz

0.5 Hz

NORMAL OPERATING

MODE RATIO

−

fCLK/92 160

fCLK/184 320

fCLK/368 640

POWER-SAVING

MODE RATIO

−

fCLK/15 360

fCLK/30 720

fCLK/61 440

NOMINAL BLINKING FREQUENCY

fblink (Hz)

blinking off

2

1

0.5

1998 May 04

16

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