ATMEL AVR 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

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)