General Description
The EM78871 is an 8-bit CID (Call Identification) RISC type microprocessor with low power, high speed CMOS technology. Integrated onto a single chip are on chip watchdog (WDT), RAM, program ROM, programmable real time clock/counter, external/internal interrupt, power down mode, LCD driver, FSK decoder, Call waiting decoder, DTMF receiver, Programming Tone generator, build-in KEY TONE clock generation, Comparator and tri-state I/O. The EM78871 provides a single chip solution to design a CID of calling message display.

Feature
CPU
• Operating voltage range : 2.2V~5.5V(Normal mode), 2.0V~5.5V(Green mode)
• 32K×13 on chip Program ROM
• 4K×8 on chip data RAM
• 144 byte working register
• Up to 51 bi-directional tri-state I/O ports (32 shared with LCD Segment pins)
• IO with internal Pull high, wake-up and interrupt functions
• STACK: 32 level stack for subroutine nesting
• TCC: 8-bit real time clock/counter (TCC) with 8-bit prescaler
• COUNTER1: 8-bit counter with 8-bit prescaler can be an interrupt source
• COUNTER2: 8-bit counter with 8-bit prescaler can be an interrupt source
• Watch Dog : Programmable free running on chip watchdog timer
• CPU modes:
• 13 interrupt source , 8 external , 5 internal
• Key Scan : Port key scan function up to 16x4 keys
• Sub-Clock: 32.768KHz crystal
• Main-clock: 3.5862MHz multiplied by 0.25, 0.5, 1 or 3 generated by internal PLL
• Key tone output :4KHz, 2KHz ,1KHz (shared with IO)
• Comparator: 3-channel comparators: internal (16 level) or external reference voltage. (shared with IO)
• Serial Peripheral Interface (SPI): Interrupt flag available for the read buffer full, Programmable baud rates of communication, Three-wire synchronous communication. (shared with IO)

Application
1. adjunct units
2. answering machines
3. feature phones