DS1339 Maxim, DS1339 Datasheet - Page 18

• Manufacturer Part Number: DS1339
• Description: The DS1339 serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output
• Manufacturer: Maxim

Figure 7. Data Write—Slave Receiver Mode
Figure 8. Data Read (from Current Pointer Location)—Slave Transmitter Mode
Figure 9. Data Read (Write Pointer, Then Read)—Slave Receive and Transmit
S - Start
A - Acknowledge (ACK)
P - Stop
S - Start
Sr - Repeated Start
A - Acknowledge (ACK)
P - Stop
A - Not Acknowledge (NACK)
S - Start
A - Acknowledge (ACK)
P - Stop
A - Not Acknowledge (NACK)
2) Slave Transmitter Mode (Read Mode): The first byte is received and handled as in the slave receiver
S
S
<Slave Address>
<Slave Address>
XXXXXXXX
S
<Data(n)>
sets the register pointer on the DS1339, with the DS1339 acknowledging the transfer. The master may
then transmit zero or more bytes of data, with the DS1339 acknowledging each byte received. The
address pointer increments after each data byte is transferred. The master generates a STOP condition to
terminate the data write.
mode. However, in this mode, the direction bit indicates that the transfer direction is reversed. Serial data
is transmitted on SDA by the DS1339 while the serial clock is input on SCL. START and STOP conditions
are recognized as the beginning and end of a serial transfer
byte received after the START condition is generated by the master. The slave address byte contains the
7-bit DS1339 address, which is 1101000, followed by the direction bit (R/W), which is 1 for a read. After
receiving and decoding the slave address byte the slave outputs an acknowledge on the SDA line. The
DS1339 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 address pointer is incremented after each byte is transferred.
The DS1339 must receive a “not acknowledge” to end a read.
1101000
1101000
1101000
0
A
1
A
A
0
XXXXXXXX A XXXXXXXX A
<Data(n+1)>
A
<Word Address (n)>
XXXXXXXX
XXXXXXXX
Master to slave
Slave to master
<Word Address (n)>
XXXXXXXX
<Data(n)>
Slave to master
Master to slave
Slave to master
Master to slave
A
A
<Data(n+2)>
A
XXXXXXXX A XXXXXXXX A
XXXXXXXX
Sr
<Data(n+1)>
<Data(n)>
<Slave Address>
1101000
18 of 20
NOTE: LAST DATA BYTE IS FOLLOWED BY A NACK
(X+1 BYTES + ACKNOWLEDGE)
NOTE: LAST DATA BYTE IS FOLLOWED BY A NACK
A XXXXXXXX
...
DATA TRANSFERRED
(X+1 BYTES + ACKNOWLEDGE)
1
XXXXXXXX A P
<Data(n+1)>
<Data(n+X)>
A
(X+1 BYTES + ACKNOWLEDGE)
<Data(n+2)>
DATA TRANSFERRED
DATA TRANSFERRED
(Figure
A
8). The slave address byte is the first
...
...
DS1339 I
<Data(n+X)>
XXXXXXXX A P
XXXXXXXX
<Data(n+X)>
2
C Serial Real-Time Clock
A P