SMH4044 Datasheet, PDF (17/20 Pages) Summit Microelectronics, Inc. – Compact PCI Hot-Swap Controller With IPMI Support

SMH4044
Preliminary
Random Address Read
Random address Read operations allow the Master to
access any memory location in a random fashion. This
operation involves a two-step process. First, the Master
issues a Write command which includes the Start condi-
tion and the Slave address field (with the R/W bit set to
Write) followed by the address of the word it is to read.
This procedure sets the internal address counter of the
SMH4044 to the desired address. After the word address
Acknowledge is received by the Master, it immediately
reissues a Start condition followed by another Slave
address field with the R/W bit set to Read. The SMH4044
will respond with an Acknowledge and then transmit the
8 data bits stored at the addressed location. At this point
the Master sets SDA high (NACK) and generates a Stop
condition. The SMH4044 discontinues data transmission
and reverts to its standby power mode.
Sequential Read
Sequential Reads can be initiated as either a current
address Read or a 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, the Master now responds with an Acknowl-
edge, indicating that it requires additional data from the
SMH4044. The SMH4044 continues to output data for
each Acknowledge received. The Master terminates the
sequential Read operation with a NACK and issues a Stop
condition.
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 rollover and the memory
will continue to output data.
S
T
A
R
R
/
Master _T
W
NS
A
AT
C
CO
K
KP
SDA
1 01 0 xxxRxxx ^{xxxxx xx xx}
Slave
A
C
K
2057 Fig10
Figure 10. Basic Read
Optional
S
T
S
A
R
T
R
/
O
Master _T
W
P
SDA
1 0 1 0 ^{x x} xW x x x x x x x x x x x x
Slave
A
A
A
C
C
C
K
K
K
2057 Fig11
Figure 11. Basic Write
SUMMIT MICROELECTRONICS, Inc.
2057 1.x 8/16/01
17