NT68F63L

The NT68F63L is a specialized monitor microcontroller from NOVATEK Microelectronics, designed for controlling CRT and LCD computer monitors. Built around a classic 8-bit 6502 CPU core, this highly integrated MCU provides all the functions needed for monitor control, including display timing management, On-Screen Display (OSD) support, user input handling, and DDC/EDID communication. The device features 32KB of MTP (Multiple Time Programmable) Flash memory for firmware storage, 512 bytes of RAM for working memory and stack, and 2KB of Boot ROM for factory programming. A key feature is the 13 channels of 8-bit PWM (Pulse Width Modulation) DAC outputs, which are used to control monitor parameters such as brightness, contrast, RGB gain and offset, and geometry adjustments. The 4-channel ADC is primarily used for key detection, allowing front-panel button scanning with minimal I/O pins. The built-in Hsync/Vsync signal processor handles synchronization signal detection and processing, supporting autosync multi-sync monitor operation. Two I2C bus interfaces enable communication with the display scalar chip and DDC/EDID data exchange with the host computer. The 128 bytes of RAM dedicated to EDID data eliminates the need for a separate EEPROM in many designs, reducing BOM cost.

The NT68F63L operates as the main control MCU in a monitor system, managing all user-facing and control functions: 1) CPU Core: The 6502 8-bit CPU executes firmware stored in the 32KB Flash memory. The 2KB Boot ROM handles initial boot and factory programming operations. 2) Timing and Sync Processing: The internal Hsync/Vsync processor receives horizontal and vertical sync signals from the video input (VGA or other analog input), measures their frequencies, and determines the display mode. This enables autosync operation where the monitor automatically adjusts to different input resolutions. 3) PWM DAC Control: The 13 8-bit PWM DACs generate analog control voltages for various monitor parameters. These are typically used for: brightness, contrast, R/G/B gain and offset controls, horizontal/vertical position and size, and other analog adjustments in CRT monitors or backlight control in LCD monitors. 4) ADC and Key Scanning: The 4-channel ADC reads the front panel keypad inputs. Typically, a resistor ladder network connects multiple buttons to a single ADC input, allowing many keys to be read with just a few ADC channels. 5) I2C Communication: The two I2C interfaces serve different purposes: – I2C0 (primary): Communication with the display scalar/graphics processor – I2C1 (secondary): DDC communication with the host computer for EDID and MCCS 6) OSD Control: The MCU controls the On-Screen Display by sending commands to the scalar chip or by directly generating simple OSD patterns, allowing the user to adjust monitor settings through an on-screen menu. 7) Watchdog Timer: The WDT monitors firmware execution and resets the MCU if the firmware hangs, improving system reliability. 8) EDID Management: 128 bytes of RAM store EDID data for DDC1/2B communication, enabling plug-and-play operation with the host computer.

• CRT and LCD computer monitor control MCUs
• Monitor OSD (On-Screen Display) controllers
• Multi-sync autosync monitor timing control
• Display DDC/EDID management and communication
• Front panel keypad scanning and user interface
• Brightness, contrast, and color control systems
• USB monitor implementations
• Industrial and medical display controllers