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b)

Data acknowledge response (ACK signal)

When transferring data, the receiver generates a confirmation response (ACK signal, low active) each time an 8-bit data segment

is received. If there is no ACK signal from the receiver, it indicates that normal communication has not been established. (This

does not include instances where the master device intentionally does not generate an ACK signal.)

Immediately after the falling edge of the clock pulse corresponding to the 8th bit of data on the SCL line, the transmitter releases

the SDA line and the receiver sets the SDA line to low (= acknowledge) level.

After transmitting the ACK signal, if the Master remains the receiver for transfer of the next byte, the SDA is released at the

falling edge of the clock corresponding to the 9th bit of data on the SCL line. Data transfer resumes when the Master becomes the

transmitter.

When the Master is the receiver, if the Master does not send an ACK signal in response to the last byte sent from the slave, that

indicates to the transmitter that data transfer has ended. At that point, the transmitter continues to release the SDA and awaits a

STOP condition from the Master.

PT0205(02/07)

Ver: 1

16

Data Sheet

PT7C4337

Real-time Clock Module (I

2

C Bus)

SCL from Master

1

2

8

9

SDA from transmitter

(sending side)

SDA from receiver

(receiving side)

Release SDA

Low active

ACK signal