STV-366-R01 STMICROELECTRONICS [STMicroelectronics], STV-366-R01 Datasheet - Page 19

• Manufacturer Part Number: STV-366-R01
• Description: 1.8V optical mouse sensor
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

VT5366
6.2.2
The byte following the address byte contains the address of the first data byte (also referred
to as the index ). The serial interface can address up to 256 byte registers.
Figure 9.
Message interpretation
All serial interface communications with the sensor must begin with a start condition. If the
start condition is followed by a valid address byte then further communications can take
place. The sensor will acknowledge the receipt of a valid address by driving the sda wire
low. The state of the read/~write bit (LSB of the address byte) is stored and the next byte of
data, sampled from sda, can be interpreted.
During a write sequence the second byte sent is an address index and is used to point to
one of the internal registers. The receiver will automatically increment the index address by
one location after each slave acknowledge. The master can therefore send data bytes
continuously to the slave until the slave fails to provide an acknowledge or the master
terminates the write communication with a stop condition or sends a repeated start , (Sr) .
As data is received by the slave it is written bit by bit to a serial/parallel register. After each
data byte has been received by the slave, an acknowledge is generated, the data is then
stored in the internal register addressed by the current index.
During a read message, the next byte read from the slave device are the contents of the
register addressed by the current index. The contents of this register are then parallel
loaded into the serial/parallel register and clocked out of the device by scl.
At the end of each byte, in both read and write message sequences, an acknowledge is
issued by the receiving device. A positive acknowledge involves holding the SDA line LOW,
a negative acknowledge involves releasing the SDA line to be pulled HIGH. Although the
VT5366 is always considered to be a slave device, it acts as a transmitter when the bus
master requests a read from the sensor.
A message can only be terminated by the bus master, either by issuing a stop condition, a
repeated start condition or by a negative acknowledge after reading a complete byte during
a read operation.
S
Sensor acknowledges valid address
address[7:1]
Serial interface data format (write ex)
R/W
R/W bit
A
INDEX[7:0]
A
Acknowledge from slave
DATA[7:0]
DATA[7:0]
Serial control bus
A
A
P
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