Preliminary W742E81A/W742C81A
1. GENERAL DESCRIPTION
4-BIT MICROCONTROLLER
The W742E81A/W742C81A is a high-performance 4-bit microcontroller (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 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 16-levels subroutine nesting
for interrupt applications. The W742E81A/W742C81A 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.
2. FEATURES
• Operating voltage: 2.4V−3.8V
• Dual-clock operation or single-clock operation (By option)
• Main-oscillator
− Connect to 3.58 MHz crystal or 400 KHz that can be selected by option code
− Crystal or RC oscillator can be selected by code option (W742E81A)
− Connect to 2 MHz typical RC oscillator (W742C81A)
• Sub-oscillator
− Connect to 32768 Hz crystal only
• Memory
− 16384 x 16 bits program flash EEPROM (including 64K x 4 bit look-up table)
− 2048 x 4 bits 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(RC)
− Input/output ports: 3 ports/12 pins(RA, RB & RD)
− High sink current output port for LED driving: 1 port /4 pins(RE)
− Port for output only: 1 port/ 4 pins(RF)
• Power-down mode
− Hold function: no operation (main-oscillator and sub-oscillator still operate)
− Stop function: no operation (main-oscillator and sub-oscillator are stopped)
− Dual-clock slow operation 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 interrupts (RC Port)
Publication Release Date: April 2000
-1-
Revision A1