PAS6311LT Datasheet, PDF (9/18 Pages) Pixart Imaging Inc. – CMOS VGA DIGITAL IMAGE SESNSOR

PAS6311LT Specification
4. I2C^TM Bus
PAS6311LT supports I2C bus transfer protocol and acts as slave device. The 7-bits unique slave address
is “1000000” and supports receiving / transmitting speed as maximum 400KHz.
4.1. I2C Bus Overview
z Only two wires SDA ( serial data ) and SCL ( serial clock ) carry information between the
devices connected to the I2C bus. Normally both SDA and SCL lines are open collector
structure and pulled high by external pull-up resistors.
z Only the master can initiates a transfer ( start ), generates clock signals, and terminates a
transfer ( stop ).
z Start and stop condition : A high to low transition of the SDA line while SCL is high defines
a start condition. A low to high transition of the SDA line while SCL is high defines a stop
condition. Please refer to Figure 4.1.
z Valid data : The data on the SDA line must be stable during the high period of the SCL clock.
Within each byte, MSB is always transferred first. Read / Write control bit is the LSB of the
first byte. Please refer to Figure 4.2.
z Both the master and slave can transmit and receive data from the bus.
z Acknowledge : The receiving device should pull down the SDA line during high period of the
SCL clock line when a complete byte was transferred by transmitter. In the case of a master
received data from a slave, the master does not generate an acknowledgment on the last byte
to indicate the end of a master read cycle.
Figure 4.1 Start and Stop conditions
Figure 4.2 Valid Data
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PixArt Imaging Inc.
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v1.5 2007/10/02