STV0676 ,CMOS DIGITAL CAMERA CO-PROCESSORFEATURESCMOS image sensors offers highly integrated■ Real-time video - up to 30fps VGAimaging produ ..
STV0676 ,CMOS DIGITAL CAMERA CO-PROCESSORabsolute maximum ratings 144.2 STV0676 AC/DC characteristic 14Chapter 5 Pinout and pin descriptions ..
STV0676 ,CMOS DIGITAL CAMERA CO-PROCESSORgeneral description .51.2 Video processor (VP) ........51.2.1 Sensor interface 51.2.2 Video process ..
STV0681 , DUAL-MODE DIGITAL CAMERA CO-PROCESSOR
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T7024 ,The T7024 is a monolithic SiGe transmit/receive front-end IC with power amplifier, low-noise amplifier and T/R switch driver. It is especially designed for operation in TDMA systems like Bluetooth and WDCT.Features Single 3-V Supply Voltage High Power-added Efficient Power Amplifier (P Typically 23 dBm ..
T7024 ,The T7024 is a monolithic SiGe transmit/receive front-end IC with power amplifier, low-noise amplifier and T/R switch driver. It is especially designed for operation in TDMA systems like Bluetooth and WDCT.Features Single 3-V Supply Voltage High Power-added Efficient Power Amplifier (P Typically 23 dBm ..
T7024 ,The T7024 is a monolithic SiGe transmit/receive front-end IC with power amplifier, low-noise amplifier and T/R switch driver. It is especially designed for operation in TDMA systems like Bluetooth and WDCT.Features Single 3-V Supply Voltage High Power-added Efficient Power Amplifier (P Typically 23 dBm ..
T7024 ,The T7024 is a monolithic SiGe transmit/receive front-end IC with power amplifier, low-noise amplifier and T/R switch driver. It is especially designed for operation in TDMA systems like Bluetooth and WDCT.Features Single 3-V Supply Voltage High Power-added Efficient Power Amplifier (P Typically 23 dBm ..
T7024 ,The T7024 is a monolithic SiGe transmit/receive front-end IC with power amplifier, low-noise amplifier and T/R switch driver. It is especially designed for operation in TDMA systems like Bluetooth and WDCT.Features Single 3-V Supply Voltage High Power-added Efficient Power Amplifier (P Typically 23 dBm ..
STV0676
CMOS DIGITAL CAMERA CO-PROCESSOR
STV0676CMOS Digital Camera Co-processor
The STV0676 co-processor combined with ST
CMOS image sensors offers highly integrated
imaging products which deliver USB 1.1, RGB-
preview, YCrCb or M-JPEG digital video data at up
to 30 frames per second.
The STV0676 interfaces to CIF (352 x 288) or VGA
(640 x 480) image sensor and performs:
- pixel defect correction,
- auto exposure, auto gain,
- auto white balance, anti-aliasing, anti-flicker,
- colour interpolation, colour balance,
- gamma correction,
- M-JPEG compression.
STV0676 chipsets are supported by a fully-featured
USB driver. This provides a wide range of user
definable settings for optimum camera setup and
operation. Isochronous data transfer over USB
guarantees video quality at all times, irrespective of
the number of other peripherals.
Low power consumption, highly integrated designs
and simple support circuitry enable OEMs to design
low cost, low power, camera products for high
volume consumer market places.
STMicroelectronics offers camera manufacturers
rapid-to-market camera products supported by
comprehensive reference designs, software drivers
and technical backup.
KEY FEATURES Real-time video - up to 30fps VGA USB 1.1 compliant Motion-JPEG compression Isochronous USB data transfer Direct Show driver support Programmable vendor ID RGB-preview, YCrCb or M-JPEG video output Automatic exposure, gain and white balance
APPLICATIONS
USB camera:- Biometric identification, toys and games
Embedded applications support:- PDA, notebook PC, mobile phone
- Set top box, and security applications
STV0676
Table of contents
Chapter 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51.1 STV0676 co-processor general description .........................................................................5
1.2 Video processor (VP) ...........................................................................................................5
1.2.1 Sensor interface ...................................................................................................5
1.2.2 Video processor functions ....................................................................................6
1.3 Auto exposure and gain control ...........................................................................................7
1.4 Defect correction ..................................................................................................................7
1.5 Video compression (VC) engine ..........................................................................................7
1.6 Control processor .................................................................................................................7
1.7 Power management .............................................................................................................7
Chapter 2 External interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82.1 USB interface .......................................................................................................................8
2.2 Mode selection .....................................................................................................................9
2.3 Selecting VID and PID via the digiport .................................................................................9
2.4 Serial EEPROM .................................................................................................................10
2.4.1 EEPROM format and contents ...........................................................................11
2.4.2 Strings ................................................................................................................11
2.4.3 CheckSum .........................................................................................................12
2.5 I2C slave mode ..................................................................................................................12
2.6 Digiport ...............................................................................................................................12
2.7 General purpose input and output ......................................................................................12
Chapter 3 STV0676 application example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .133.1 USB webcam .....................................................................................................................13
3.2 Embedded camera .............................................................................................................13
Chapter 4 Detailed specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144.1 STV0676 absolute maximum ratings .................................................................................14
4.2 STV0676 AC/DC characteristic ..........................................................................................14
Chapter 5 Pinout and pin descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .155.1 STV0676 pin details ...........................................................................................................15
STV0676
Chapter 6 Package Details STV0676 64pin TQFP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Chapter 7 Reference design and evaluation kits (RDK’s and EVK’s) . . . . . . . . . . . . . . . .20
Chapter 8 Ordering details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Chapter 9 Design issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
STV0676
Document revision history
Table 1 : Document revision history
STV0676 Overview Overview
1.1 STV0676 co-processor general descriptionThe STV0676 is a digital video processor requiring no external RAM and a minimum of passive
support components to provide a complete USB camera. STV0676 accepts raw digital video data
from a ST VGA or CIF format CMOS sensor and is capable of transferring the resulting JPEG data
to a host PC over USB at rates up to 30 frames per second VGA.
The internal STV0676 architecture consists of a number of separate functional blocks: Video processor (VP) Video compressor (VC) USB control block General purpose controller
The VP controls the sensor and processes the raw RGB pixel data into YCbCr images.
This YCbCr data is compressed by the VC.
The USB control block transfers the compressed data to the host PC.
1.2 Video processor (VP)
1.2.1 Sensor interfaceThe VP interfaces directly to the image sensor. The sensor interface comprises: 5-wire data bus SDATA[4:0] for receiving both video data and embedded timing references, 2-wire serial control interface (SSDA, SSCL), sensor clock SCLK reset circuitry sensor suspend control
Overview STV0676
1.2.2 Video processor functionsSTV0676 provides a master clock SCLK to the camera module. Each 10-bit pixel value generated
by the sensor is transmitted across the 5 wire databus SDATA[4:0] as a pair of sequential 5-bit
nibbles, most significant nibble first. Codes representing the start and end frames and the start and
end of lines are embedded within the video data stream to allow the video processor to synchronise
with the video data stream.
The video processing engine performs the following functions on incoming data: full colour restoration at each pixel site from Bayer-patterned input data, matrixing/gain on each colour channel for colour purity, peaking for image clarity, gamma correction, colour space conversion from raw RGB to YCbCr[4:2:2].
The 2-wire sensor serial interface (SSDA and SSCL) provides control of sensor configuration.
Note: the MSBit SDATA5 of the databus is unused in the current application but it will support future
sensors where a 12bit ADC architecture may be used.
Figure 1: Block diagram of STV0676 video processor module
STV0676 Overview
1.3 Auto exposure and gain controlThe STV0676 automatically controls the sensor exposure, which is evaluated (and, where
necessary modified) once per frame, where a frame consists of 2 video fields. The video fields are
identical in length, that is, they do not contain any of the half line detail of the analogue video
standards like CCIR or NTSC. Two fields per frame are required by the internal sensor video timing
model. Integration time, sensor analogue gain and STV0676 digital gain are all used to control the
overall exposure. The STV0676 exposure algorithm uses an asymptotic approach in calculating the
change required in the present exposure value to approach the requested exposure target.
1.4 Defect correctionSTV0676 automatically detects and corrects pixel defects without the need for any additional
components or sensor calibration procedures. This greatly simplifies camera assembly and test
when compared with previous EEPROM-based defect correction schemes. The pixel defect
correction scheme ensures that the STV0676 + ST CMOS sensor appears as a ‘defect free’
chipset.
1.5 Video compression (VC) engineThe video compression engine performs 3 main functions: up scaling of input YCbCr 4:2:2 video stream from the VP (typically to scale from QVGA to CIF
image formats), compression and encoding of YCbCr stream into Motion-JPEG (M-JPEG) format, USB bandwidth monitoring.
The data stream from the VP can be up to VGA size. The scaler in VC can downsize this image.
Once scaled the video stream is then converted into M-JPEG format. M-JPEG simply treats video
as a series of JPEG still images. The conversion is realised via a sequential DCT (discrete cosine
transform) with Huffman encoding. After transfer over USB, the M-JPEG stream is decoded in the
device driver running on the host.
The VC module is capable of compression ratios of up to 100:1 although this is scene-dependent.
Image framerate produced by the STV0676 chipset is fixed and furthermore the available USB
bandwidth is also fixed (within the software driver). The VC module varies the compression ratio to
match the fluctuating input video data rates to the available USB bandwidth and required framerate.
The final stage of the VC block manages the data transfer from the local VC FIFO store to the USB
core. STV0676 performs this management automatically by employing long-term (frame-level) and
short-term (block-level) compression management.
1.6 Control processorThe embedded 8052 microprocessor core controls the data flow through the major sub blocks
within STV0676 as well as the I2 C communications to reconfigure the VP corresponding to requests
from the device driver.
1.7 Power managementThe chipset conforms to all power requirements specified by USB Version 1.1.
External interfaces STV0676 External interfaces
2.1 USB interfaceThe USB interface is designed to be compliant with version 1.1 of the USB specification. The
STV0676 is a low power device and is therefore suitable for connection to any USB port on a PC,
self-powered hub or when connected to a bus-powered hub.
The device complies with the device framework specified in Chapter 9 of the USB specification as
follows: The device supports a single high power configuration (Configuration 1). Endpoint 0 is the default control endpoint and is always supported. Endpoint 0 supports all of the USB commands required by the device framework. Vendor specific commands on Endpoint 0 are used for all device control. Configuration 1 supports a single interface (interface 0). Interface 0 supports 8 alternate settings (alternates 0-7). The alternate settings support between 0 and 2 additional endpoints. Endpoint 1 is used for isochronous transfer of image data. Endpoint 3 is used for transferring status information, e.g. state of a hardware button. The endpoints are configured as follows (Table 2) in the alternate settings:
The best and most consistent performance in terms of image quality is always obtained in the
highest bandwidth setting (alternate 7). Under some circumstances it may not be possible for the
host to allocate this amount of USB bandwidth to the device.
The isochronous settings reserve varying quantities of bandwidth - from 10% to 85% of USB
bandwidth. The lower settings result in poor image quality due to heavy compression applied to
maintain a high framerate streaming of image data, but at the same time leaving more bandwidth
free for other USB devices. This is desirable if more than one camera is to be used, or if there are
other isochronous peripherals connected. The device driver allows the user to specify the maximum
bandwidth they wish to allocate to transfer data from the device. If the maximum specified by the
user is not available, perhaps because another isochronous device has already reserved that
bandwidth, then lower alternates are tried until one succeeds.
Table 2: Endpoint alternate settings
STV0676 External interfacesBenchmark testing of the STV0676 indicates that 30fps CIF video (compressed) can be
accommodated in 50% of USB bandwidth.
2.2 Mode selectionAll USB devices report a VID, PID and power consumption as part of a standard device descriptor.
The VID and PID for STV0676 can be configured by the state of the digiport bits or by using an
external EEPROM. The mode selection is made using the two MODESEL pins as described in
Table 3 below.
2.3 Selecting VID and PID via the digiportTables 4~7 demonstrate how the VID/PID information is defined via the digiport.
The current reference design for the STV0676-chipset has digiport[7:0] connected to VSS, thus the
VID and PID are 16’h0553 and 16’h0140 respectively.
The digiport also controls the device current consumption that is reported to the host at device
enumeration.
Table 3: Mode selection
Table 4: Basic digiport configuration
Table 5: Digiport LS nibble configuration
External interfaces STV0676
2.4 Serial EEPROMSTV0676 is designed to be used with a 128 or 256 byte serial I2 C EEPROM. The EEPROM can be
programmed with data to allow a user to fully customise the USB identity of STV0676. The
configuration of this data is as follows.
Table 6: Master VID/PID selection The ‘x’ ls nibble of the PID is defined by the value from Table 5 above
Table 7: Device power consumption indicator
Table 5: Digiport LS nibble configuration
STV0676 External interfaces
2.4.1 EEPROM format and contentsThe remaining space is available for the string blocks indexed at locations 8, 9 and 10.
2.4.2 StringsThe strings referred to above (locations 8-10), are the USB string descriptors referenced from the
device, configuration and interface descriptors. The value should be set to ’0’ if the string is not
implemented or to the offset in bytes of the start of the string block in the EEPROM.
The first byte of each string block is the number of the characters in the string. Subsequent bytes
are the actual string, which need not include a terminating null (Table9:).
Table 8: EEPROM format and contents
Table 9: EEPROM device string example
