ht82m75r Holtek Semiconductor Inc., ht82m75r Datasheet - Page 43

• Manufacturer Part Number: ht82m75r
• Description: I/o Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

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
Rev. 1.10
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.
Acknowledge Polling Flow
Byte Write Timing
43
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.
HT82M75R/HT82M75RE
HT82K75R/HT82K75RE
June 11, 2010