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USB2.0 PC Camera Controller with Image Signal Processing and MJPEG Encoder
General Description

The RTS5821 is a USB 2.0 compliant camera controller designed for notebook and desktop PCs. The built-in extremely low-power transceiver provides superior compatibility with USB hosts and high quality for image applications. It is fully compliant with the USB Video Class, and operates with native drivers provided in Windows XP, Windows Vista, Windows 7, and Windows 8 operating systems.

The RTS5821 integrates a USB 2.0 transceiver that is optimized for high performance data transfer rate, high speed MCU (Micro Processor Unit), DC-to-DC regulators, sensor controller, image signal processing engine, MJPEG compression into a single chip. It supports most available CMOS sensors from VGA (640x480) to UXGA (1600x1200) resolution.

The RTS5821 is designed to support various types of access interface to achieve the best compatibility with major SOC CMOS image sensors.

The RTS5821 supports both an internal MCU program ROM and an external NOR-Flash interface. With the external Nor-flash interface (100-pin LQFP package, a DVP package to provide a friendly debugging environment), the control firmware could be easily re-configured via a USB link. This could ease the software developing work and shorten the prototyping schedule.

A new generation ISP (Image Signal Processing) engine supports most UVC defined image adjustments. In addition, this engine also has offers functions such as Lens Shading Correction, dead pixel cancellation, G1G2 filter, Color Correction Matrix, histogram statistic Auto White Balance, scaling function and so on. These functions help compensate for intrinsic inaccuracy in lens and image sensors to provide better image quality. The internal scaling filter can scale down higher resolutions for size reduction purposes

The RTS5821 integrates five regulators to save BOM cost and PCB area. One 5V-to-3.3V regulator converts USB bus power to 3.3V power for device I/O. Two 3.3V-to-1.2~3.1V adjustable regulator converts 3.3V to 1.2~3.1V power for the sensor’s analog and IO parts. Two 3.3V-to-1.2V regulators convert 3.3V power to 1.2 core power for the RTS5821. 

A significant feature of the RTS5821 is enhanced power management. Its power consumption is 20% lower than similar controllers. With multiple regulators, an integrated image signal processing engine and motion JPEG encoder, the RTS5821 consumes less power from the USB bus whether in normal operation, standby, or suspend mode

General System Features
  • USB2.0/1.1 PC Camera Controller with Image Signal Processing engine and MJPEG encoder
  • USB Video Class compliant, works with native driver in Microsoft Windows XP 32-bit/64-bit, VISTA 32-bit/64-bit, Windows 7 32-bit/64-bit, and Windows8 32-bit/64-bit operating systems
  • On-chip high-performance and low-power MCU
  • SPI (Serial Peripheral Interface, Mode 0~Mode 3) connection to external serial flash for switching code and configuring customized parameters
  • Embedded 64K ROM, 3.5Kbytes SRAM, 6Kbytes ring Buffer
  • On chip firmware default supports major sensors without external serial flash
  • Upgradeable firmware and customized parameters through USB interface
  • Software controlled connection to USB bus for re-enumeration
  • Motion JPEG hardware encoder integrated
  • Built in 5.0V to 3.3V regulator output for I/O power
  • Built in 3.3V to 1.2V regulator for internal core power
  • Built in 3.3V to 1.2V~3.1V adjustable regulator output for image sensor analog circuitry & IO power
  • Adjustable and dynamic frame rate control on USB transaction
  • Automatic frame rate adjustment when exposure is in low light environment
  • Selective suspend to minimize power consumption
  • Supports 3 GPIO (General Purpose Input/Output) pins with programmable driving strength
  • LED indicator on video streaming through GPIO
  • Supports property page write back in serial flash cache mode
  • 32-pin QFN ‘Green’ package
  • Memory BIST (Built-In Self Test) integrated
USB Controller
  • Compliant with USB Specification 2.0/1.1 Full-Speed and High-Speed transfer mode
  • Compliant with USB Video Class Specification Rev1.0 required for Windows XP, Vista, Windows 7, and Windows 8
  • Support 3 Endpoints:
    • End Point 0: Control endpoint
    • End Point A: Video Streaming Isochronous IN endpoint with varying packaged size
    • End Point C: Interrupt IN endpoint
  • Supports Suspend and Remote Wake-Up mode
  • Built in Self-Loop-Back BIST for testing purposes
Sensor Controller
  • Supports 10 bits raw image data (Bayer pattern) format from sensor
  • Supports 16 bits YUV (4:2:2) input format from sensor
  • Supports standard 2-wire serial interface for sensor control
  • Wide range (2MHz to 96MHz, default 24MHz) and programmable system clock output for sensor
  • Programmable VSYNC and HSYNC timing and polarity to support various sensors from 3rd party vendors
  • Supports major brands of CMOS sensors up to 2 Mega Pixels
    • OmniVision OV7675, OV7725, OV9660, OV9665, OV2650, OV2655, OV9710, OV9726
    • Aptina MI-0360 (MT9V011), MI-1330 (MT9M113), MI-2030 (MT9D113), MI1040
    • Samsung S5K4B2F, S5K6A1GX
Micro Controller Unit
  • Variable clock speed (15MHz/20MHz/24MHz) for performance and power saving
  • Total 64K bytes code memory including embedded 64K bytes mask ROM and 3.5K bytes SRAM
  • Firmware is upgradeable, with fast on-the-fly configuration of EEPROM and serial flash through the USB interface
  • Software controlled connection to USB bus for re-enumeration
  • Watchdog control for MCU reset and interrupt
  • Configurable VID (Vendor ID), PID (Product ID), and serial number string from external serial flash
  • Loadable 8K bytes of firmware from external serial flash to replace part of embedded firmware
  • Supports customized parameters for UVC (USB Video Class) defined and Realtek proprietary functions from external serial flash
Image Signal Processing (ISP) Engine
  • 3rd generation ISP with line buffer width 1600 pixels
  • Programmable global Gamma correction (UVC defined)
  • Sharpness enhancement and smooth processing (UVC defined)
  • Auto Exposure and Manual Exposure adjustment (UVC defined)
  • Automatic White Balance (AWB) adjustment (UVC defined)
  • Manual White Balance control according to color temperature setting (UVC defined)
  • High friendly brightness adjust, RGB domain (UVC defined)
  • Dynamic contrast adjust, RGB domain (UVC defined)
  • High friendly saturation adjust, RGB domain (UVC defined)
  • Hue processing (UVC defined)
  • Backlight compensation (UVC defined)
  • Power line flicker compensation (UVC defined)
  • Individual Lens Shading Correction for R/G/B channels
  • Negative, Mono and Gray Processing
  • G1G2 compensation filter
  • Programmable gamma table, R/G/B individual curve and Y gamma block.
  • Black Level Compensation for individual R/G/B channels
  • Static dead pixels cancellation, up to 80 pixels information stored in serial flash
  • Dynamic dead pixel detection and cancellation
  • Edge detection and enhancement
  • Input pattern interpolation and noise reduction
  • Global and individual gain control for R/G/B channels
  • Configurable Color Correction Matrix for R/G/B channels
  • AWB (Auto White Balance) control with both White Point and Gray World algorithm
  • AE (Auto Exposure) adjustment with Y channel of histogram statistic
  • Zoom In and Zoom Out image from sensor, and output with various resolution
  • Sharpness Block: Detects in all directions
  • YUV offset and gain after Y domain edge enhancement
Motion JPEG Encoder Engine
  • 60MHz operation clock rate, maximum up to 96MHz
  • Supports compression resolution up to UXGA (1600H x 1200V)
  • Compliant with USB Video Class MJPEG payload
  • Programmable compression ratio depends on transport bandwidth and image quality option
Video/Still Image Output Formats
  • Supports up to 2M resolution for still image capture
  • Uses UVC still image capture method 2 (Isochronous transaction)
  • Supports YUV420 video format
  • Supports RGB Bayer pattern bypass output mode
  • Supports USB Video Class uncompressed YUV (4:2:2) and USB Video Class MJPEG video, and still image format output. The maximum output frame rate of these two video formats in various USB operation modes is listed in the following tables.

Software Features

  • USB Video Class compliant, works with native drivers in Microsoft Windows XP 32-bit/64-bit, VISTA 32-bit/64-bit, Windows 7 32-bit/64-bit and Windows 8 32-bit/64-bit systems
  • Provides certified logo driver for Microsoft Windows XP, VISTA, Windows 7, and Windows 8 operating systems
  • Linux UVC driver, open source at
  • Intuitive Control Panel (Realtek Camera Manager) to enhance user experience
    • Enables face tracking function for single and multiple users
    • Digital Zoom-In and Zoom-Out processing
    • Video and voice streaming recording
    • Still image capture
    • Interface for R/G/B gamma curve adjustment
    • Provide various preset image styles for video streaming and still captured image
  • Selective suspend function to save power in Standby mode
  • Notebook PCs
  • Netbook PCs
  • All-In-One PCs
  • Ultra mobile devices


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