General Description

The EM78862C is an 8-bit RISC type microprocessor with low power, high speed CMOS technology. Integrated into the single chip are built-in watchdog (WDT), RAM, ROM, programmable real-time clock/counter, internal interrupt, power-down mode, LCD driver, and bi-directional I/O. The EM78862C provides a single chip solution for scientific calculator design applications.

Features

CPU

„ Operating voltage range: 2.2V ~ 3.6V

„ 16K x 13 on-chip ROM

„ 1.25K x 8 on-chip RAM

„ 144 byte working register

„ Up to 24 bi-directional I/O ports (16 shared with LCD segment pins)

„ 8 level stack for subroutine nesting

„ 8-bit real time clock/counter (TCC) can be configured as interrupt sources with prescaler

„ Two sets of 8 bit counters are set asinterrupt sources with prescaler

„ Programmable free running on-chip watchdog timer

„ Four modes (internal PLL clock 3.579MHz)

   •  SLEEP Mode: CPU and 3.579MHz clock turn off, 32.768kHz clock turn off

   •  IDLE Mode: CPU and 3.579MHz clock turn off, 32.768kHz clock turn on

   •  GREEN Mode: 3.579MHz clock turn off, CPU and 32.768kHz clock turn on

   •  NORMAL Mode: 3.579MHz clock turn on, CPU and 32.768kHz clock turn on

„ Input port wake up function

„ Six interrupt sources: three internal, three external

   •  Internal:

      1. TCIF for TCC timer overflow interrupt

      2. CNT1 for COUNTER 1 overflow interrupt

      3. CNT2 for COUNTER 2 overflow interrupt

  •  External:

     1. INT 0 for Port 70, Port 71, Port 72, or Port 73, has a falling edge trigger interrupt

     2. INT 1 for Port 74, Port 75, or Port 76, has a falling edge trigger interrupt

     3. INT 3 for Port 77 has a rising edge or falling edge trigger (by CONT register) interrupt

„ 67-pin die chip (EM78862CH)

„ Port key scan function

„ Clock frequency 32.768kHz or RC mode

LCD

„ LCD operation voltage:4.5 V ( VDD must be fixed at 3V )

„ Common driver pins:16

„ Segment driver pins:32

„ 1/4 bias

„ 1/16 duty

 Applications

„ Data Bank

„ Message display box

„ Scientific calculator