SMH4042A
SequentialRead
Random Address Read
Random address Read operations allow the Master to Sequential Reads can be initiated as either a current
access any memory location in a random fashion. This address Read or a random access Read. The first word
operation involves a two-step process. First, the Master is transmitted as with the other byte read modes (current
issues a write command which includes the start condi- address byte Read or random address byte Read).
tion and the Slave address field (with the R/W bit set to However, the Master now responds with an Acknowl-
edge, indicating that it requires additional data from the
This procedure sets the internal address counter of the SMH4042A. The SMH4042A continues to output data for
SMH4042Atothedesiredaddress. Afterthewordaddress
Write) followed by the address of the word it is to read.
each Acknowledge received. The Master terminates the
Acknowledge is received by the Master, it immediately sequentialReadoperationwithaNACKandissuesaStop
reissues a start condition followed by another Slave condition. During a sequential read operation the internal
addressfieldwiththeR/WbitsettoRead. TheSMH4042A
address counter is automatically incremented with each
will respond with an Acknowledge and then transmit the Acknowledge signal. For read operations all address bits
8 data bits stored at the addressed location. At this point areincremented,allowingtheentirearraytobereadusing
the Master sets SDA high (NACK) and generates a Stop a single Read command. After a count of the last memory
condition. TheSMH4042Adiscontinuesdatatransmission
and reverts to its standby power mode.
address the address counter will roll-over and the
memory will continue to output data.
S
T
N S
A
R
T
R
/
W
A
C
K
A T
C O
K P
Optional
Master
SDA
x x x
x x x x x x x x
x x
x x
R
1 0 1 0
A
C
K
Slave
2070 Fig09
Figure 9. Basic Read
S
T
A
R
T
S
T
O
P
R
/
W
Master
SDA
x x x
x x x x x x x x
x x
x x
1 0 1 0
W
A
C
K
A
C
K
A
C
K
Slave
2070 Fig10
Figure 10. Basic Write
SUMMIT MICROELECTRONICS, Inc.
2070 9.1 5/27/03
13
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
