General Description

The EM78870 is an 8-bit RISC type microprocessor with low power, high speed CMOS technology. Integrated onto a single chip are on_chip watchdog (WDT), RAM, ROM, programmable real time clock /counter, internal interrupt, power down mode, LCD driver, build-in KEY TONE clock generation, Programming Tone generators, Serial Peripheral Interface(SPI), comparator and tri-state I/O. The EM78870 provides a single chip solution to design a 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

• 2.5K× 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:

• 12 interrupt source : 8 external , 4 internal

• Key Scan : Port key scan function up to 16x4 keys

• Sub-Clock: 32.768kHz crystal

• Main-clock: 3.5826MHz multiplied by 0.25, 0.5, 1 or 3 generated by internal PLL

• Key tone output (shared with IO) : 4kHz, 2kHz, 1kHz

• 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)

Programmable Tone Generators

• Operation Voltage 2.2V〜5.5V

• Programmable Tone1 and Tone2 generators

• Independent single tone generation for Tone1 and Tone2

• Mixed dual tone generation by Tone1 and Tone2 with 2dB difference

LCD (8x80, 9x80, 16x80, 24x72)

• Maximum common driver pins : 16/24

• Maximum segment driver pins : 80(SEG0..SEG79)/72(SEG8..SEG79)

• Shared COM16 ~ COM23 pins with SEG0 ~ SEG7 pins

• 1/4 bias for 8, 9 and 16 common mode and 1/5 bias for 24 common mode

• 1/8, 1/9, 1/16, 1/24 duty

• 16 Level LCD contrast control (software)

• Internal resistor circuit for LCD bias

• Internal voltage follower for better display

Package type

• 128-pin QFP or chip : EM78870AQ (POVD disable), EM78870BQ (POVD enable), EM78870H

Application

Cordless phones or any telephone product with large LCD needed