ht82m9aae Holtek Semiconductor Inc., ht82m9aae Datasheet - Page 18

• Manufacturer Part Number: ht82m9aae
• Description: Usb Mouse Encoder 8-bit Mcu With Eeprom
• Manufacturer: Holtek Semiconductor Inc.

Data EEPROM Functional Description
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Memory Organization
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Device Operations
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Rev. 1.20
Serial clock (SCL)
The SCL input is used for positive edge clock data into
each EEPROM device and negative edge clock data
out of each device.
Serial data (SDA)
The SDA pin is bidirectional for serial data transfer.
The pin is open-drain driven and may be wired-OR
with any number of other open-drain or open collector
devices.
1K Serial EEPROM
Internally organized with 128 8-bit words, the 1K re-
quires an 8-bit data word address for random word ad-
dressing.
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).
Byte Write Timing
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Device Addressing
The 1K EEPROM devices all require 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.
The next three bits are the fixed to be ²0².
The 8th bit of 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.
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.
HT82M9AEE/HT82M9AAE
August 13, 2007