SMS2916 Просмотр технического описания (PDF) - Summit Microelectronics

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SMS2916

Voltage Supervisory Circuit With Watchdog Timer

Summit Microelectronics 

SMS2902/SMS2904/SMS2916

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 ACKnowledge,

indicating that it requires additional data from the

SMS29xx. The SMS29xx 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 11 for the

address, acknowledge and data transfer sequence.

Acknowledges from SMS29xx

Acknowledge from

Master Receiver

Lack of

Acknowledge from

Master Receiver

SDA Bus

Activity

A

A

A

10

A

9

X

R

W

C

Word Address

C

K

K

A

A

X X X R C First Data Byte C

W

K

K

Last Data Byte

1

01

0

A

10

A

9

X

0

S

T Device

A Type

R Address

T

Read/Write

0= Write

Slave Address

AA AA AA AA

76 54 32 10

1010

1

S

T Device

A Type

R Address

T

Read/Write

1= Read

Slave Address

DD DD DD DD

76 54 32 10

DD DD DD DD

76 54 32 10 1

S

T

O

P

Lack of ACK (low)

determines last

data byte to be read

Master sends Read

request to Slave

Master Transmitter

to

Slave Receiver

Master Writes Word

Address to Slave

Master Transmitter

to

Slave Receiver

Master Requests

Data from Slave

Master Transmitter

to

Slave Receiver

Slave sends

Data to Master

Slave Transmitter

to

Master Receiver

Slave sends

Data to Master

Slave Transmitter

to

Master Receiver

Slave Transmitter

to

Master Receiver

Shading Denotes

SMS29xx

SDA Output Active

Slave Transmitter

to

Master Receiver

Slave Transmitter

to

Master Receiver

Master Transmitter

to

Slave Receiver

2028 ILL13.1

FIGURE 11. SEQUENTIAL READ OPERATION (starting with a Random Address READ)

2028 5.0 4/18/00

11

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