GENERAL DESCRIPTION
The W742C810 is a high-performance 4-bit microcontroller (mC) that provides an LCD driver. The device contains a 4-bit ALU, two 8-bit timers, two dividers (for two oscillators) in dual-clock operation, a 40 ´ 4 LCD driver, six 4-bit I/O ports (including 1 output port for LED driving), and one channel DTMF generator. There are also five interrupt sources and 8-level subroutine nesting for interrupt applications. The W742C810 operates on very low current and has one power reduction mode, that is the dual-clock slow operation, which helps to minimize power dissipation.

FEATURES
● Operating voltage: 2.4V-3.6V
● Dual-clock operation
● Main oscillator
   - Connect to 3.58 MHz crystal only
● Sub-oscillator
   - Connect to 32768 Hz crystal only
● Memory
   - 8192 x 16 bit program ROM (including 32K x 4 bit look-up table)
   - 1024 x 4 bit data RAM (including 16 nibbles x 16 pages working registers)
   - 40 x 4 LCD data RAM
● 24 input/output pins
   - Port for input only: 1 ports/4 pins
   - Input/output ports: 3 ports/12 pins
   - High sink current output port for LED driving: 1 port /4 pins
   - Port for output only: 1 port/ 4 pins
● Power-down mode
   - Hold function: no operation (main oscillator and sub-oscillator still operate)
   - Stop function: no operation (only main oscillator stops but sub-oscillator still operates)
   - Dual-clock slow mode: system is operated by the sub-oscillator (FOSC = Fs and Fm is stopped)
● Five types of interrupts
   - Four internal interrupts (Divider0, Divider1, Timer 0, Timer 1)
   - One external interrupt (RC Port)
● LCD driver output
   - 40 segments x 4 commons
   - 1/4 duty 1/3 bias driving mode
   - Clock source should be the sub-oscillator clock in the dual-clock operation mode
● MFP output pin
   - Output is software selectable as modulating or nonmodulating frequency
   - Works as frequency output specified by Timer 1
● DTMF output pin
   - Output is one channel Dual Tone Multi-frequency signal for dialling
● Two built-in 14-bit frequency dividers
   - Divider0: the clock source is the output of the main oscillator
   - Divider1: the clock source is the output of the sub-oscillator
● Two built-in 8-bit programmable countdown timers
   - Timer 0: one of two internal clock frequencies (FOSC/4 or FOSC/1024) can be selected
   - Timer 1: with auto-reload function, and one of three internal clock frequencies (FOSC, FOSC/64 or Fs) can be selected by MR1 register; the specified frequency can be delivered to MFP pin
● Built-in 18/15-bit watchdog timer selectable for system reset; enable the watch dog timer or not is determined by code option
● Powerful instruction set: 131 instructions
● 8-level subroutine (include interrupt) nesting