DS1672
13 of 15
with the DS1672 acknowledging each byte received. The register pointer will increment after each
byte is transferred. The master will generate a stop condition to terminate the data write.
2) Slave transmitter mode (DS1672 read mode): The first byte is received and handled as in the slave
receiver mode. However, in this mode, the direction bit will indicate that the transfer direction is
reversed. Serial data is transmitted on SDA by the DS1672 while the serial clock is input on SCL.
START and STOP conditions are recognized as the beginning and end of a serial transfer (Figure 8).
The slave address byte is the first byte received after the START condition is generated by the master.
The slave address byte contains the 7-bit DS1672 address, which is 1101000, followed by the
direction bit (R/W), which for a read is a 1. After receiving and decoding the slave address byte the
DS1672 outputs an acknowledge on the SDA line. The DS1672 then begins to transmit data starting
with the register address pointed to by the register pointer. If the register pointer is not written to
before the initiation of a read mode the first address that is read is the last one stored in the register
pointer. The DS1672 must receive a “not acknowledge” to end a read.
Figure 6. Data Transfer on I
2
C Serial Bus
MSB
slave address
R/W
direction
bit
SDA
SCL
START
CONDITION
1 2 6 7 8 9
1 2 8 9
STOP CONDITION
OR
REPEATED
START CONDITION
3 - 8
acknowledgement
signal from receiver
acknowledgement
signal from receiver
ACK ACK
repeated if more bytes
are transferred
Figure 7. Data Write: Slave Receiver Mode
AXXXXXXXXA1101000S 0 XXXXXXXX A XXXXXXXX A XXXXXXXX A P
<Slave Address> <Word Address (n)> <Data(n) <Data(n+1)> <Data(n+X)>
S - START
A - ACKNOWLEDGE
P - STOP
<RW>
R/W - READ/WRITE OR DIRECTION BIT ADDRESS = D0H
DATA TRANSFERRED
(X+1 BYTES + ACKNOWLEDGE)
