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