Z89305

The Z89303/05/07 Digital Television Controllers are application-specific controllers designed to provide complete audio and video control of television receivers, video recorders, with advanced on-screen display facilities. The Z89303/05/07 are 24K, 16K and 12K ROM versions in 52-pin SDIP packages. The powerful 12 MHz Z89C00 RISC processor core allows the user to control the onboard peripheral functions and registers using the standard processor instruction set.

The extensive character attributes can be controlled in two modes: by the on-screen display controller character control mode for maximum display control flexibility, and closed caption mode for optimum display of closed caption text.

Closed caption text can be decoded directly from the composite video signal with the assistance of the processor's digital signal processing capabilities and displayed on the screen. The character representation in this mode allows for a simple attribute control through the insertion of control characters, and each word of RAM specifies two displayed characters.

The character control mode provides access to the full set of attribute controls. Each word of RAM specifies a single displayed character and basic character attributes, allowing the modification of attributes on a character-by-character basis. The insertion of control characters permits direction of other character attributes.

The fully customized 512 character set, formatted in two 256 character banks, can be displayed with a host of display attributes that incude underlining, italics, blinking, eight foreground/background colors, character position offset delay, and background transparency. The 16-bit display character representation allows the modification of some key attributes on a character-by-character basis. A character's pixel array is stored as a 16- or 18-word representation in Character Graphics ROM (CGROM). The ROM contents are referenced by a 16-bit word stored in video RAM (VRAM) defining the character type and its key attributes.

Serial interfacing with the television tuner is provided through the tuner serial port. Other serial devices, such as digital channel tunning adjustments, may be accessed through the industry standard I2C port.

Additional hardware provides the capability to displ ay two times normal size characters. The smoothing logic contained in the on-screen display circuit improves the appearance of larger fonts. Fringing circuitry can be activated to improve the visibiity of text by surrounding the character lines with a one-pixel border.

RGB outputs provide the direct video signals, and a blanking output is provided to control the video multiplexor. Dot clock and verticle line synchronization are normally obtained from H_FLYBACK and V_FLYBACK, but can be generated by the Z89303/05/047, and driven to the external deflection unit through the bidirectional SYNC ports when external video synchronization signals are not present.

User control can be monitored through the keypad scanning port, or the 16-bit remote control capture register. Receiver functions such as color and volume can be directly controlled by eight 8-bit pulse width modulated ports. All nine PWM ports are available in the 52-pin package.

The Z89303/05/07 has two internal 12 MHz VCOs that are referenced to a 32 KHz internal oscillator to provide the system clock. In Sleep mode, the controller uses the 32 KHz clock for the system clock to reduce power consumption. The processor can be suspended by placing it into STOP mode when main power is not available for minimal power consumption.