BU9890GUL-W Datasheet, PDF (9/14 Pages) Rohm – Silicon Monolithic Integrated Circuit

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◇DEVICE OPERATION
○START CONDITION (RECOGNITION OF START BIT)
・All commands are proceeded by the start condition, which is a HIGH to LOW transition
of SDA when SCL is HIGH.
・The device continuously monitors the SDA and SCL lines for the start condition and
will not respond to any command until this condition has been met.
（See Fig.-4 SYNCHRONOUS DATA TIMING）
○STOP CONDITION (RECOGNITION OF STOP BIT)
・All commands must be terminated by a stop condition, which is a LOW to HIGH
transition of SDA when SCL is HIGH.
（See Fig.-4 SYNCHRONOUS DATA TIMING）
○NOTICE ABOUT WRITE COMMAND
・In the case that stop condition is not excuted in WRITE mode, transfered data will not
be written in a memory.
○DEVICE ADDRESSING
・Following a START condition, the master output the slave address to be accessed.
・The most significant four bits of the slave address are the “device type indentifier,”
for this device it is fixed as “1010” and next three bit set to “000”.
・The last bit of the stream (R/W … READ/WRITE) determines the operation to be
performed. When set to “1”, a read operation is selected ; when set to “0”, a write
operation is selected.
R/W set to “0” ･ ･ ･ ･ ･ ･ ･ ･ WRITE (including word address input of Random Read)
R/W set to “1” ･ ･ ･ ･ ･ ･ ･ ･ READ
１０１０
０
０
０
Ｒ／Ｗ
○WRITE PROTECT (WP)
When WP pin set to VCC(H level), write protect is set for 4,096 words (all address).
When WP pin set to GND(L level), it is enable to write 4,096 words (all address).
Either control this pin or connect to GND ( or Vcc). It is inhibited from being left
unconnected.
REV. A