AT90S/LS4434 and AT90S/LS8535

2

Block Diagram

The AVR core combines a rich instruction set with 32 gen-

eral 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 through-

puts up to ten times faster than conventional CISC micro-

controllers.

The AT90S4434/8535 provides the following features:

4K/8K bytes of In-System Programmable Flash, 256/512

bytes EEPROM, 256/512 bytes SRAM, 32 general purpose

I/O lines, 32 general purpose working registers, RTC, three

flexible timer/counters with compare modes, internal and

external interrupts, a programmable serial UART, 8-chan-

nel, 10-bit ADC, programmable Watchdog Timer with inter-

nal oscillator, an SPI serial port and three software

selectable power saving modes. The Idle mode stops the

CPU while allowing the SRAM, timer/counters, SPI port

and interrupt system to continue functioning. The Power

Down mode saves the register contents but freezes the

oscillator, disabling all other chip functions until the next

interrupt or hardware reset. In Power Save mode, the timer

oscillator continues to run, allowing the user to maintain a

timer base while the rest of the device is sleeping.

The device is manufactured using Atmel’s high density

non-volatile memory technology. The on-chip ISP Flash

PROGRAM

COUNTER

INTERNAL

OSCILLATOR

WATCHDOG

TIMER

STACK

POINTER

PROGRAM

FLASH

MCU CONTROL

REGISTER

SRAM

GENERAL

PURPOSE

REGISTERS

INSTRUCTION

REGISTER

TIMER/

COUNTERS

INSTRUCTION

DECODER

DATA DIR.

REG. PORTB

DATA DIR.

REG. PORTA

DATA DIR.

REG. PORTD

DATA DIR.

REG. PORTC

DATA REGISTER

PORTB

DATA REGISTER

PORTA

ANALOG MUX

ADC

DATA REGISTER

PORTD

DATA REGISTER

PORTC

PROGRAMMING

LOGIC

TIMING AND

CONTROL

OSCILLATOR

OSCILLATOR

INTERRUPT

UNIT

EEPROM

SPI

UART

STATUS

REGISTER

Z

Y

X

ALU

PORTB DRIVERS

PORTA DRIVERS

PORTD DRIVERS

PORTC DRIVERS

PB0 - PB7

PA0 - PA7

RESET

VCC

AVCC

AGND

AREF

GND

XTAL2

XTAL1

CONTROL

LINES

PD0 - PD7

PC0 - PC7

8-BIT DATA BUS