HT82K74E datasheet(17/56 Pages) HOLTEK

17 / 56 page

HT82K74E/HT82K74EE

Rev. 1.00

December 15, 2009

· 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.

Refer to Random read timing.

· 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 receives an

acknowledgment, it will continue to increment 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

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

D e v i c e 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

N o A C K

Current Read Timing

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

D A T A n

S t o p

S t a r t

S D A

A C K

D A T A n + 1

D A T A n + x

N o A C K

Sequential Read Timing

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

W o r d a d d r e s s

A C K

S t o p

S t a r t

S D A

A C K

N o A C K

A C K

D A T A

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

S t a r t

Random Read Timing

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