Description The AT90S/LS2323 and AT90S/LS2343 are low-power, CMOS, 8-bit microcontrollers based on the AVR RISC architecture. By executing powerful instructions in a single clock cycle, the AT90S2323/2343 achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed. The AVR core combines a rich instruction set with 32 general-purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers. Block Diagram Figure 1. The AT90S/LS2343 Block Diagram VCC 8-BIT DATA BUS INTERNAL OSCILLATOR GND PROGRAM COUNTER STACK POINTER WATCHDOG TIMER PROGRAM FLASH SRAM MCU CONTROL REGISTER INSTRUCTION REGISTER INSTRUCTION DECODER CONTROL LINES TIMING AND CONTROL RESET TIMER/ COUNTER GENERAL PURPOSE REGISTERS X Y Z INTERRUPT UNIT ALU EEPROM STATUS REGISTER PROGRAMMING LOGIC SPI DATA REGISTER PORTB DATA DIR. REG. PORTB PORTB DRIVERS PB0 -PB4 2 AT90S/LS2323/2343 1004D–09/01