SMS8198
Sequential READ
Sequential READs can be initiated as either a current
address READ or random access READ. The first word is
transmitted as with the other byte read modes (current
address byte READ or random address byte READ);
however, themasternowrespondswithanACKnowledge,
indicating that it requires additional data from the
SMS8198. The SMS8198 continues to output data for
each ACKnowledge received. The master terminates the
sequential READ operation by not responding with an
ACKnowledge, and issues a STOP conditions.
During a sequential read operation, the internal address
counter is automatically incremented with each acknowl-
edge signal. For read operations, all address bits are
incremented, allowing the entire array to be read using a
single read command. After a count of the last memory
address, the address counter will ‘roll-over’ and the
memory will continue to output data. See Figure 10 for the
address, acknowledge and data transfer sequence.
Lack of
Acknowledge from
Master Receiver
Acknowledge from
Master Receiver
Acknowledges from SMS8198
A
C
K
A
C
K
A
C
K
A
C
SDA Bus
Activity
A
10
A
9
A
8
R
W
A
10
A
9
A
8
R
W K
Word Address
First Data Byte
Last Data Byte
A
7
A
6
A
5
A
4
A
3
A
2
A
1
A
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
1 0 1 0
0
1 0 1 0
1
1
S
T
S
T
A
R
T
S
T
O
P
Device
Type
Device
Type
A
A10,A9,A8
A10,A9,A80
R Address
T
Address
Read/Write
0= Write
Read/Write
1= Read
Lack of ACK (low)
determines last
data byte to be read
Slave Address
Slave Address
Master sends Read
request to Slave
Master Writes Word
Address to Slave
Master Requests
Data from Slave
Slave sends
Data to Master
Slave sends
Data to Master
Master Transmitter
to
Master Transmitter
to
Master Transmitter
to
Slave Transmitter
to
Slave Transmitter
to
Slave Receiver
Slave Receiver
Slave Receiver
Master Receiver
Master Receiver
Slave Transmitter
to
Master Transmitter
to
Slave Transmitter
to
Slave Transmitter
to
Master Receiver
Slave Receiver
Master Receiver
Master Receiver
2036 ILL12.0
Shading Denotes
SMS8198
SDA Output Active
Figure 10. Sequential READ Operation (starting with a Random Address READ)
2036 5.0 4/18/00
10
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
