STV-366-R01 STMICROELECTRONICS [STMicroelectronics], STV-366-R01 Datasheet - Page 20

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

Serial control bus
6.3
6.3.1
6.3.2
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Types of messages
This section gives guidelines on the basic operations to read data from and write data to the
serial interface.
The serial interface supports variable length messages. A message may contain no data
bytes, one data byte or many data bytes. This data can be written to or read from common
or different locations within the sensor. The range of instructions available are detailed
below.
Examples of these operations are given below. A full description of the internal registers is
given in the previous section. For all examples, the slave address used is 32
and 33
while this bit is set in the read address.
Single location, single data write
When a random value is written to the sensor, the message looks as shown in
Figure 10. Single location, single write
In this example, the fineH exposure register (index = 32
zero for writing and the Inc. bit (MSB of the index byte) is set to zero to disable automatic
increment of the index after writing the value. The address index is preserved and may be
used by a subsequent read. The write message is terminated with a stop condition from the
master.
Multiple location write
It is possible to write data bytes to consecutive adjacent internal registers without having to
send explicit indexes prior to sending each data byte. An auto-increment write is
assumed if no stop condition occurs.
Figure 11. Multiple location write
–
–
10
Start
S
for reading. The write address includes the read/write bit (the LSB) set to zero
A write message with no data byte is used to set the index for a subsequent read
message.
Multiple location writes may be used for faster information transfers.
S
address
Device
20h
20h
A
Ack
A
0
16
Index
32h
A
@ index = 16
data written
11
A
10
) is set to 85
Incremental write
A
Data
85h
@ index = 17
data written
C1
10
. The r/w bit is set to
A
10
Stop
Figure 10
for writing
A
P
P
VT5366
.