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SMS24

Highly Programmble Voltage Supervisory Circuit

Summit Microelectronics 

SMS24

ment the current address pointer. When the SMS24

receives the slave address field with the R/W bit set to “1”

it issues an acknowledge and transmits the 8-bit word

stored at address location n+1. The current address byte

read operation only accesses a single byte of data. The

master does not acknowledge the transfer, but does

generate a stop condition. At this point the SMS24

discontinues data transmission.

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 condition

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 SMS24

to the desired address. After the word address

acknowlthe R/W bit set to READ. The SMS24 will respond

with an acknowledge and then transmit the 8-data bits

stored at the addressed location. At this point the master

does not acknowledge the transmission but does gener-

ate the stop condition. The SMS24 discontinues data

transmission and reverts to its standby power mode.

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, the master now responds with an ACKnowl-

edge, indicating that it requires additional data from the

SMS24. The SMS24 continues to output data for each

ACKnowledge received. The master terminates the se-

quential READ operation by not responding with an AC-

Knowledge, and issues a STOP condition. During a

sequential read operation the internal address counter is

automatically incremented with each ACKnowledge sig-

nal. 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.

SUMMIT MICROELECTRONICS, Inc.

2048 2.4. 3/1/01

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