W99681CF Datasheet, PDF (7/78 Pages) Winbond – JPEG USB Dual Mode Camera Chip

W99681CF
1 GENERAL DESCRIPTION
The W99681CF is a digital video processing chip offered by Winbond to facilitate adapterless
connection between digital video camera and personal computer for video and still image capturing and
editing, video e-mail, and video conferencing applications. Low-cost, high-performance, and high-
quality digital video camera can be realized by using Winbond′s W99681CF, which includes Universal
Serial Bus (USB) technology and the international standard JPEG compression.
The digital video camera is becoming the next great input device for the PC. USB is now a common PC
standard for connecting peripheral products, which features low cost, hot-attachable plug and play,
adequate 12 Mb/s full speed bandwidth, and simultaneous attachment of multiple devices. The
W99681CF has built-in full speed USB controller which benefits from using the isochronous data
transfer mode of the USB bus, and which is compliant with the full power management requirements of
the USB specification, including startup, operating, and suspend modes. To prevent saturation of the
USB bus, the W99681CF uses no more than 8 Mb/s of available bandwidth to ensure the continued
operation of other low bandwidth devices such as USB mice and keyboards.
Although USB provides a low-cost solution for low to medium speed peripherals, its 12 Mb/s bandwidth
is not enough for high-quality and high-performance digital video camera. High-quality and low-cost
compression is necessary to boost frame rate for a high-performance digital video camera. The
W99681CF has built-in the baseline JPEG compression, which corresponds to the ISO/IEC
international standard 10918-1, with YCbCr4:2:2 or YCbCr4:2:0 components in non-interleaved scan.
The baseline JPEG implementation in the W99681CF includes Discrete Cosine Transform (DCT),
quantization, zig-zag scan, and Huffman encoder. With JPEG compression, the W99681CF can easily
achieve good quality 30 frames per second (fps) in CIF resolution (352×288) and 10~15 fps in VGA
resolution (640×480) by consuming no more than 8 Mb/s USB bandwidth.
The W99681CF can accept NTSC, PAL, or VGA video in 8- or 16-bit YCbCr4:2:2 format, square or
rectangular pixels, and converts to sub-QCIF (128×96), QCIF (176×144), CIF (128×96), SIF (352×240),
320×240, or VGA (640×480) format. Built-in cropping window control and arbitrary scaling in both the
horizontal and vertical directions can serve as the digital pan and zoom over a user-specified region for
camera control.
In addition to USB interface, the W99681CF also supports an 8-bit microcontroller interface for portable
PC camera applications. Up to 24 still images in 640×480 VGA format can be captured, JPEG
compressed, and stored into an external 2 Mbytes Flash memory when in the portable mode.
An on-chip DRAM controller is used to interface to SDRAM or EDO DRAM through a 16-bit data bus.
An external serial E²PROM is also supported if IHV-specific Vendor ID and Product ID are needed. The
IHV-specific information can be also provided by an external microcontroller if present to save the cost
of an E²PROM. The W99681CF is a 3.3 V device with TTL-compatible 3.3 V or 5.0 V I/O, and is
packaged in a 128L QFP.
Publication Release Date: March 2000
-7-
Revision A1