HT45R22E Holtek Semiconductor, HT45R22E Datasheet - Page 19

• Manufacturer Part Number: HT45R22E
• Description: Remote Type 8-bit OTP MCU
• Manufacturer: Holtek Semiconductor

Device Operations
Device Addressing
The 8K EEPROM device requires an 8-bit device ad-
dress word following a start condition to enable the chip
for a read or write operation. The device address word
consist of a mandatory one, zero sequence for the first
four most significant bits (refer to the diagram showing
the Device Address). This is common to all the
EEPROM device.
These page addressing bits on the 8K device should be
considered the most significant bits of the data word ad-
dress which follows.
Rev. 1.00
Clock and data transition
Data transfer may be initiated only when the bus is not
busy. During data transfer, the data line must remain
stable whenever the clock line is high. Changes in
data line while the clock line is high will be interpreted
as a START or STOP condition.
Start condition
A high-to-low transition of SDA with SCL high is a start
condition which must precede any other command
(refer to Start and Stop Definition Timing diagram).
Stop condition
A low-to-high transition of SDA with SCL high is a stop
condition. After a read sequence, the stop command
will place the EEPROM in a standby power mode (re-
fer to Start and Stop Definition Timing Diagram).
Acknowledge
All addresses and data words are serially transmitted
to and from the EEPROM in 8-bit words. The
EEPROM sends a zero to acknowledge that it has re-
ceived each word. This happens during the ninth clock
cycle.
Page Write Timing
Byte Write Timing
19
The 8th bit device address is the read/write operation
select bit. A read operation is initiated if this bit is high
and a write operation is initiated if this bit is low.
If the comparison of the device address succeed the
EEPROM will output a zero at ACK bit. If not, the chip will
return to a standby state.
Write 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 de-
vice, such as a microcontroller, must terminate the
write sequence with a stop condition. At this time the
EEPROM enters an internally-timed write cycle to the
nonvolatile memory. All inputs are disabled during this
write cycle and EEPROM will not respond until write is
complete (refer to Byte write timing).
Page write
The 8K EEPROM is capable of a 16-byte page write.
A page write is initiated in the same way as a byte
write, but the microcontroller does not send a stop con-
dition after the first data word is clocked in. Instead, af-
ter the EEPROM acknowledges the receipt of the first
data word, the microcontroller can transmit up to 15
more data words. The EEPROM will respond with a
ze ro a f t e r e a c h d a t a w o r d r e c e i v e d . T h e
microcontroller must terminate the page write sequence
with a stop condition (refer to Page write timing).
The data word address lower four bits are internally in-
cremented following the receipt of each data word.
The higher data word address bits are not incre-
mented, retaining the memory page row location.
HT45R22E
March 17, 2010
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