HT82K75R datasheet(43/66 Pages) HOLTEK

43 / 66 page

HT82M75R/HT82M75RE

HT82K75R/HT82K75RE

Rev. 1.10

June 11, 2010

If the comparison of the device address is successful

then the EEPROM will output a zero as an ACK bit. If

not, the EEPROM will return to a standby state.

Device Operations

· Byte Write

A write operation requires an 8-bit data word address

following the device address word and acknowledg-

ment. Upon receipt of this address, the EEPROM will

again respond with a zero and then clock in the first

8-bit data word. After receiving the 8-bit data word, the

EEPROM will output a zero and the addressing device

must terminate the write sequence with a stop condi-

tion. At this time the EEPROM enters an inter-

nally-timed write cycle to the non-volatile memory. All

inputs are disabled during this write cycle and

EEPROM will not respond until the write cycle is com-

pleted.

· Acknowledge polling

To maximize bus throughput, one technique is to allow

the master to poll for an acknowledge signal after the

start condition and the control byte for a write com-

mand have been sent. If the device is still busy imple-

menting its write cycle, then no ACK will be returned.

The master can send the next read/write command

when the ACK signal has finally been received.

· Read operations

The data EEPROM supports three read operations,

namely, current address read, random address read

and sequential read. During read operation execution,

the read/write select bit should be set to 1.

· Current address read

The internal data word address counter maintains the

last address accessed during the last read or write op-

eration, incremented by one. This address stays valid

between operations as long as the EEPROM power is

maintained. The address will roll over during a read

from the last byte of the last memory page to the first

byte of the first page. Once the device address with

the read/write select bit set to one is clocked in and ac-

knowledged by the EEPROM, the current address

data word is serially clocked out. The microcontroller

should respond a No ACK - High - signal and a follow-

ing stop condition.

· Random read

A random read requires a dummy byte write sequence

to load in the data word address which is then clocked

in and acknowledged by the EEPROM. The

microcontroller must then generate another start con-

dition. The microcontroller now initiates a current ad-

dress read by sending a device address with the

read/write select bit high. The EEPROM acknowl-

edges the device address and serially clocks out the

data word. The microcontroller should respond with a

No ACK signal - high - followed by a stop condition.

· Sequential read

Sequential reads are initiated by either a current ad-

dress read or a random address read. After the

microcontroller receives a data word, it responds with

an acknowledgment. As long as the EEPROM re-

ceives an acknowledgment, it will continue to incre-

ment the data word address and serially clock out

sequential data words. When the memory address

limit is reached, the data word address will roll over

and the sequential read continues. The sequential

read operation is terminated when the microcontroller

responds with a No ACK signal - high - followed by a

stop condition.

R / W

D e v i c e A d d r e s s

R / W

D e v i c e a d d r e s s

W o r d a d d r e s s

D A T A

A C K

S t o p

S t a r t

S D A

A C K

Byte Write Timing

S e n d W r i t e C o m m a n d

S e n d S t o p C o n d i t i o n

t o I n i t i a t e W r i t e C y c l e

S e n d S t a r t

S e n d C o t r o l l B y t e

w i t h R / W = 0

( A C K = 0 ) ?

N e x t O p e r a t i o n

N o

Y e s

Acknowledge Polling Flow

HT82K75R 数据表(PDF) 43 Page - Holtek Semiconductor Inc

HT82K75R 数据表(HTML) 43 Page - Holtek Semiconductor Inc

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