PCF8534 datasheet(20/40 Pages) PHILIPS

20 / 40 page

PCF8534_0

Preliminary datasheet

Rev. 00.05 — 20 February 2007

20 of 40

NXP Semiconductors

PCF8534

Universal LCD driver for low multiplex rates

7.5 Acknowledge

The number of data bytes transferred between the START and STOP conditions from

transmitter to receiver is unlimited. Each byte of eight bits is followed by an acknowledge

bit. The acknowledge bit is a HIGH level signal put on the bus by the transmitter during

which time the master generates an extra acknowledge related clock pulse. A slave

receiver which is addressed must generate an acknowledge after the reception of each

byte. Also a master receiver must generate an acknowledge after the reception of each

byte that has been clocked out of the slave transmitter. The device that acknowledges

must pull-down the SDA line during the acknowledge clock pulse, so that the SDA line is

stable LOW during the HIGH period of the acknowledge related clock pulse (set-up and

hold times must be taken into consideration). A master receiver must signal an end of data

to the transmitter by not generating an acknowledge on the last byte that has been

clocked out of the slave. In this event the transmitter must leave the data line HIGH to

enable the master to generate a STOP condition. Acknowledgement on the I2C-bus is

illustrated in Figure 14.

7.6 PCF8534 I2C-bus controller

The PCF8534 acts as an I2C-bus slave receiver. It does not initiate I2C-bus transfers or

transmit data to an I2C-bus master receiver. The only data output from the PCF8534 are

the acknowledge signals of the selected devices. Device selection depends on the

I2C-bus slave address, on the transferred command data and on the hardware

subaddress.

Fig 13. System configuration

mga807

SDA

SCL

MASTER

TRANSMITTER/

RECEIVER

MASTER

TRANSMITTER

SLAVE

TRANSMITTER/

RECEIVER

SLAVE

RECEIVER

MASTER

TRANSMITTER/

RECEIVER

Fig 14. Acknowledgement of the I2C-bus

mbc602

START

condition

clock pulse for

acknowledgement

not acknowledge

acknowledge

data output

by transmitter

data output

by receiver

SCL from

master

PCF8534 Datasheet(PDF) 20 Page - NXP Semiconductors

PCF8534 Datasheet(HTML) 20 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Datasheet Download

Link URL