Motorola A920 Service Manual page 97

A920: Camera
Real Time Data
Transmission
Storage
FLASH
SD
MMC
Description
The Conexant imager allows15 fps(frames per second) image readouts at VGA resolution. The Conexant imager will output raw Bayer RGB 8-bit/pixel data to the
Conexant backend processor (U7600).
The Conexant backend processor will receive the Bayer RGB data from the imager and process the image data into 8-bit YUV uncompressed or compressed data that is
send through the VODATA bus to the Helen application processor. U7600 can process the YUV data in VGA(640x480), QVGA(320x240), CIF(352x288), and
QCIF(176x144) output resolutions. Control functions for U7600 are done through a 2-wire serial interface(SSCLK and SSDA).
The QCIF qualifier logic devices(U7602 and U7603) are used for viewfinder and video capture functions. VSYNC and HSYNC signals provide vertical and horizontal
synchronization of the image signals. VSYNC indicates a start and end of a valid video frame while HSYNC indicated the start and end of a valid video line.
VODATA sends 8-bit processed image data in YUV 4:2:2 format to the Helen processor. VODATA3 is shared by the camera and IrDA devices. Due to the hardware
restrictions, Camera and IrDA wouldn't work simultaneously. For this reason, IRDA_SHUTDOWN is used to enable VODATA3 during camera operation.
CAM_ROT_DETECT is used to indicate the rotated position of the imager. A magnet integrated in the Conexant imager will activate the Hall effect switch and cause a
state change for CAM_ROT_DETECT. The Helen will respond with a horizontal inversion of the image.
The image that Helen receives goes through a DSP pre-processing stage where the YUV 4:2:2 is converted to YUV 4:2:0. To display the image on the unit's display, the
YUV 4:2:0 signal passes through a DSP post-processing stage and converts it to RGB. The RGB signal is then passed through a video buffer and to the display. For still
image storage cases, the YUV 4:2:0 image passes through JPEG encoding and then transferred to a user selectable storage device(Flash, SD, MMC). For video cases, the
YUV 4:2:0 image is passed through MPEG4 or H.263 encoding. The video is then transferred to a user selectable storage device or sent as real time data transmission.
LCD
208x320
TFT 65K color
Video
Reset*
Buffer
YUV 4:2:0
VSYNCO, HSYNCO
to
RGB
VODATA3
YUV 4:2:2
to
Video VODATA[7:0]
YUV 4:2:0
MPEG4/H.263
Encoding
CAM_ICLK
U7602
Still Image
JPEG
Latch
Qualifier
Encoding
Clock
SSCK, SSDA
I2C
IRDA_Shutdown
SUSPEND
GPIO
HELEN
CAM_ROT_DETECT
IrDa_RX
Reset*
Vcc
U7605
Conexant
Backend
Processor
ASIC
XIN
U7600
QCIF
PIXCLK
PIXVLD
Logic
Master I2C
Suspend
VAUX4_3V
Reset*
VSync, HSync
Conexant
DATA[7:0]
ICLK
MSCK, MSDA
Slave
VAUX4_3V
Hall-Effect Switch
PCAP
Vcc
CMOS
Imager