Functional description, Ptn3501 maintenance and control device, Acknowledge (see figure 6) – Philips PTN3501 User Manual

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Philips Semiconductors

Product specification

PTN3501

Maintenance and control device

2001 Jan 17

Acknowledge (see Figure 6)

The number of data bytes transferred between the start and the stop
conditions from transmitter to receiver is not limited. Each byte of
eight bits is followed by one acknowledge bit. The acknowledge bit
is a HIGH level put on the bus by the transmitter whereas 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 must generate an
acknowledge after the reception of each byte that has been clocked

out of the slave transmitter. The device that acknowledges has to
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 account.

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.

SW00545

DATA OUTPUT

BY TRANSMITTER

DATA OUTPUT

BY RECEIVER

SCL FROM

MASTER

ACKNOWLEDGE

NOT ACKNOWLEDGE

CLOCK PULSE FOR
ACKNOWLEDGEMENT

START
CONDITION

Figure 6. Acknowledgment on the I

C-bus

FUNCTIONAL DESCRIPTION

SW00788

WRITE PULSE

DATA FROM
SHIFT REGISTER

POWER-ON
RESET

READ PULSE

DATA TO
SHIFT REGISTER

P0 TO P7

100

TO INTERRUPT LOGIC

Figure 7. Simplified schematic diagram of each I/O