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ATtiny28L/V

1062FS–AVR–07/06

Description

The ATtiny28 is a low-power CMOS 8-bit microcontroller based on the AVR RISC archi-

tecture. By executing powerful instructions in a single clock cycle, the ATtiny28 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 con-

nected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be

accessed in one single instruction executed in one clock cycle. The resulting architec-

ture is more code efficient while achieving throughputs up to ten times faster than

conventional CISC microcontrollers.

Block Diagram

Figure 1. The ATtiny28 Block Diagram

The ATtiny28 provides the following features: 2K bytes of Flash, 11 general-purpose I/O

lines, 8 input lines, a high-current LED driver, 32 general-purpose working registers, an

8-bit timer/counter, internal and external interrupts, programmable Watchdog Timer with

internal oscillator and 2 software-selectable power-saving modes. The Idle Mode stops

the CPU while allowing the timer/counter 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. The wake-up or inter-

PROGRAM

COUNTER

INTERNAL

OSCILLATOR

WATCHDOG

TIMER

STACK

POINTER

PROGRAM

FLASH

MCU CONTROL

REGISTER

GENERAL

PURPOSE

REGISTERS

INSTRUCTION

REGISTER

TIMER/

COUNTER

INSTRUCTION

DECODER

DATA REGISTER

PORTB

PROGRAMMING

LOGIC

TIMING AND

CONTROL

INTERRUPT

UNIT

STATUS

REGISTER

ALU

PORTB

VCC

GND

CONTROL

LINES

8-BIT DATA BUS

Z

OSCILLATOR

PORTD

DATA REGISTER

PORTA

PORTA

PORTA CONTROL

REGISTER

XTAL2

XTAL1

RESET

HARDWARE

STACK

DATA REGISTER

PORTD

DATA DIR

REG. PORTD

HARDWARE

MODULATOR

INTERNAL

CALIBRATED

OSCILLATOR