VV5409 View Datasheet(PDF) - Vision
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MFG CO.
'VV5409' PDF : 39 Pages View PDF
VV5409 CMOS Monochrome Sensor Datasheet (Restricted) Rev 1.0
6. Serial Control Bus
Note: Where ‘Recommended settings’ are given in Section 6.5 and Section 6.6, it is recommended that these
settings are writen to the camera registers on startup, for correct operation of the sensor. This applies to the
Setup0 [16], Setup1 [17], and at1 [121] registers in particular.
6.1 General Description
Writing configuration information to the video sensor, and reading both sensor status, and configuration
information, back from the sensor, is performed through the 2-wire serial-interface.
Communication using the serial-control-bus, centres around a number of registers internal to the video
sensor. These registers, store the sensor status, set-up, exposure, and system information. Most of the
registers are read/write, allowing the receiving equipment to change their contents. Others (such as the chip
ID) are read only.
The main features of the serial-interface include:
• Sensor address is now fixed at 20 H/21 H (whereas in VV6407, 2 possible sensor addresses could be
set by means of the SA[0] pin)
• Broadcast address, to ease setting up multiple camera configurations
• Variable length read/write messages
• Indexed addressing of information source, or destination within the sensor
• Automatic update of the index, after a read, or write message
• Message abort, with negative acknowledge, from the master
• Byte oriented messages.
The contents of all internal registers, accessible through the serial-control-bus, are encapsulated in each
start-of-field line - see Section 5.3.4.
6.2 Serial Communication Protocol
The host controller must perform the role of a communications master, while the camera acts as either a
slave receiver, or transmitter.The communication from host to camera, takes the form of 8-bit data, with a
maximum serial clock video processor frequency of 100 kHz. Since the serial clock is generated by the bus-
master, it determines the data transfer rate. Data transfer protocol on the bus is shown below.
Start condition
Acknowledge
SDA
MSB
LSB
SCL
S
12 34 5 6 7
Address or data byte
8
A
P
Stop condition
Figure 6.1 : Serial-Interface Data Transfer Protocol
6.3 Data Format
Information is packed in 8-bit packets (bytes) always followed by an acknowledge bit. The internal data is
produced by sampling SDA, at a rising edge of SCL. The external data must be stable during the high period
of SCL. The exceptions to this are start (S) or stop (P) conditions when SDA falls, or rises respectively, while
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VV5409 CMOS Monochrome Sensor Datasheet (Restricted) Rev 1.0
SCL is high.
A message contains at least two bytes, preceded by a start condition, and followed by either a stop, or
repeated start, (Sr) followed by another message.
The first byte contains the device address byte, which includes the data direction read, (r), ~write, (~w), bit.
The allocation of serial-interface addresses for sensors, VISION co-processors, and serial E2PROMs is
defined in Table 6.1.The lsb of the address byte, indicates the direction of the message. If the lsb is set high,
the master will read data from the slave, and if the lsb is reset low, the master will write data to the slave. After
the r, ~w bit is sampled, the data direction cannot be changed until the next address byte, with a new r, ~w
bit is received.
In addition to its own specific address, the VV5409 also responds to the sensor and VISION co-processor;
and sensor only, serial-interface addresses. These additional addresses allow sensors and/or VISION co-
processors to be written to in parallel, through the serial-interface bus. The broadcast addresses are only
intended for writing, not reading.
Serial Address
Comment
1010_XXX_R/W
A0H - AFH Serial E2PROM - 8 possible addresses
0010_000_R/W
20H - 21H Sensor - address (fixed).
0010_1XX_R/W
28H - 2FH VISION Co-processor - 4 possible addresses
0011_000_R/W
30H & 31H Sensor and VISION Co-processor Broadcast Address
0011_001_R/W
32H & 33H Sensor Only Broadcast Address
0011_010_R/W
34H & 35H VISION Co-processor Only Broadcast Address
Table 6.1 : Allocation of Serial-Interface Addresses
0 0 1 0 0 0 0 R/W
Figure 6.2 : VV5409 Serial Interface Address
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 128 registers. If the msb of the second byte is set, the automatic
increment feature of the address index, is selected.
Sensor acknowledges valid address
Acknowledge from slave
S address[7:1] address [0] A INC INDEX[6:0]
A DATA[7:0]
A
R/W bit
Auto increment
Index bit
DATA[7:0]
Figure 6.3 : Serial-Interface Data Format
AP
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