ht82k74e Holtek Semiconductor Inc., ht82k74e Datasheet - Page 17

• Manufacturer Part Number: ht82k74e
• Description: 27mhz Keyboard/ Mouse Tx 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

Rev. 1.00
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 Timing
Random Read Timing
Current Read Timing
Byte Write Timing
17
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.
HT82K74E/HT82K74EE
December 15, 2009