GENERAL DESCRIPTION
The W742C814 is a high-performance 4-bit micro-controller (µC) 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 32 × 4 LCD driver, five 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-levels subroutine nesting for call subroutine or interrupt applications. The W742C814 operates on very low current and has two power reduction modes, that is the dual-clock slow operation and STOP mode, which help to minimize power dissipation.

FEATURES
• Operating voltage: 2.4V - 5.5V
• Dual-clock operation mode (Connect to 32768 Hz crystal only)
    Fslow oscillator: 32768 Hz OSC
    Ffast oscillator: PLL (Phase Lock Loop) output enable
• Memory
    − 4096 x 16 bits program ROM (including 16K x 4 bit look-up table)
    − 1024 x 4 bits data RAM (including 16 nibbles x 16 pages working registers)
    − 32 x 4 LCD data RAM
• 20 input/output pins
    − Port for input only: 1 ports/4 pins (RC)
    − Input/output ports: 3 ports/12 pins (RA, RB & RD)
    − High sink current output port for LED driving: 1 port /4 pins (RE)
• Power-down mode
    − Hold function: no operation (excluding Fslow and Fosc oscillator)
    − Stop function: no operation (Fslow and Fosc oscillator are stopped)
    − Dual-clock slow operation mode: system is operated by 32768 Hz (FOSC = Fslow and Ffast stopped)
• Five types of interrupts
    − Four internal interrupts (Divider0, Divider1, Timer 0, Timer 1)
    − One external interrupts (RC Port)
• LCD driver output
    − 32 segments x 4 commons
    − 1/4 duty 1/3 bias driving mode
• MFP output pin
    − Output is software selectable as modulating or non-modulating frequency
    − Works as frequency output specified by Timer 1
• DTMF output pin (PLL should be enable in this function)
    − Output is one channel Dual Tone Multi-Frequency signal for dialing
• Two built-in 14-bit frequency dividers
    − Divider0: the clock source is the output of the Fosc-oscillator
    − Divider1: the clock source is the output of the Fslow-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; and 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
• Build-in Power-on reset detested circuit
• Powerful instruction set: 1XX instructions
• 8-levels subroutine (include interrupt) nesting