GENERAL DESCRIPTION
The W921E400A/W921C400 is a single-chip CMOS 4-bit microcontroller that is a subset of W921E880A/W921C880. It features a 4-bit ALU, three multi-function timers, one channel DTMF generator, a beep tone generator, a serial I/O port and built in four by one channel comparator circuit, thus it can be easily implemented as telephone processor. Using the serial transmit/receive function, the W921E400A/W921C400 series can interface with Winbond LCD driver IC by the serial control circuit. There are also seven interrupt sources and 48-level subroutine nesting for interrupt applications.