24LC32

DS21072G-page 8

 2004 Microchip Technology Inc.

6.3

Contiguous Addressing Across

Multiple Devices

The device select bits A2, A1, A0 can be used to

expand the contiguous address space for up to 256K

bits by adding up to eight 24LC32's on the same bus.

In this case, software can use A0 of the control byte as

address bit A12, A1 as address bit A13, and A2 as

address bit A14.

6.4

Sequential Read

Sequential reads are initiated in the same way as a ran-

dom read except that after the 24LC32 transmits the

first data byte, the master issues an acknowledge as

opposed to the stop condition used in a random read.

This acknowledge directs the 24LC32 to transmit the

next sequentially addressed 8 bit word (Figure 6-3).

Following the final byte transmitted to the master, the

master will NOT generate an acknowledge but will gen-

erate a stop condition.

To provide sequential reads the 24LC32 contains an

internal address pointer which is incremented by one at

the completion of each operation. This address pointer

allows the entire memory contents to be serially read

during one operation. The address pointer, however,

will not roll over from address 07FF to address 0000. It

will roll from 07FF to unused memory space.

6.5

Noise Protection

The SCL and SDA inputs have filter circuits which sup-

press noise spikes to ensure proper device operation

even on a noisy bus. All I/O lines incorporate Schmitt

triggers for 400 kHz (Fast Mode) compatibility.

FIGURE 6-2:

RANDOM READ

FIGURE 6-3:

SEQUENTIAL READ

SDA LINE

BUS

CONTROL

BYTE

WORD

ADDRESS (1)

S

T

O

P

S

T

A

R

T

A

C

K

A

C

K

A

C

K

ACTIVITY:

A

C

K

N

O

DATA n

00 0

WORD

ADDRESS (0)

S

T

A

R

T

CONTROL

BYTE

A

C

K

0

S

S

P

P

BUS ACTIVITY

MASTER

SDA LINE

BUS ACTIVITY

S

T

O

P

CONTROL

BYTE

A

C

K

N

O

A

C

K

DATA n

DATA n + 1

DATA n + 2

DATA n + X

A

C

K

A

C

K

A

C

K