ATMELAVR 8 bit RISC

MICROCONTROLLERS

a general comparison

What does AVR RISC mean?

• The acronym AVR has been reported to stand for: Advanced Virtual RISC and also for the chip's designers: Alf-Egil Bogen and Vegard Wollan who designed the basic architecture at the Norwegian Institute of Technology.

• RISC stands for reduced instruction set computer.

CPU design with a reduced instruction set as well as a simpler set of instructions (like for example PIC and AVR)

A little history

• The PIC (Programmable Interrupt Controller) appeared around 1980.→ 8 bit bus → executes 1 instruction in 4 clk cycles→ Harvard architecture

• AVR (1994)→ 8 bit bus→ one instruction per cycle→ Harvard architecture

AVR 8-Bit RISC High Performance

• True single cycle execution→ single-clock-cycle-per-instruction execution → PIC microcontrollers take 4 clock cycles per instruction

• One MIPS (mega instructions per second) per MHz → up to 20 MHz clock

• 32 general purpose registers→ provide flexibility and performance when using high

level languages → prevents access to RAM

• Harvard architecture → separate bus for program and data memory

AVR 8-Bit RISC Low Power Consumption

• 1.8 to 5.5V operation

→ will use all the energy stored in your batteries

• A variety of sleep modes

→ AVR Flash microcontrollers have up to six different sleep modes

→ fast wake-up from sleep modes

• Software controlled frequency

AVR 8-Bit RISC Compatibility

• AVR® Flash microcontrollers share a single core architecture

→ use the same code for all families

→ 1 Kbytes to 256 Kbytes of code

→8 to 100 pins

→ all devices have

Internal oscillators

AVR 8-Bit RISC - picoPower Technology

• “PicoPower enables AVR to achieve the industry’s lowest power consumption with 650 nA with a RTC (real time clock) running and 100nA in Power Down sleep” (from ATMEL website)

• - True 1.8V Supply Voltage- Minimized Leakage Current- Ultra Low Power 32 kHz Crystal Oscillator- Digital Input Disable Registers- Power Reduction Register

So what chip should I use?

• the application chooses the chip• each family has a large number of variants • the number of pins, the package, the cost

of the chip, the peripherals, the operating voltage, the current consumption, and so forth

• PIC is more application oriented• AVR mostly pin #s and flash memory

differ

Many choices

• TI(MSP430), Zilog (Z8), Freescale (SC8), Atmel(AVR), Microchip (PIC), ST, Renesas / Hitachi (Mx or H8), Philips (8051) as just few of the many possible selections

• MICROCHIP ATMEL and MSP430

→ FREE SAMPLES

AVR has very good documentation

• Wide use

• AVRFreaks .net

• Free software

Most Importantly!!!

• Best C compiler to start programming in C→ and it is FREE

Code Vision AVR→ http://www.hpinfotech.ro/

• AVR Studio 4 also free from: http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2725

Code Vision AVR setup

• After opening Code Vision AVR click on:

→ tools

→ codewizardAVR

select you chip version and oscillator frequency

Set/clear the pins you want

LCD setup (LCD from microprocessors lab)

• Control LCD with port A:

Setting up the Analog to Digital conversion

• 8 bit A/D on channel 3 (PORTA.3)