ATMEL AVR 8 bit RISC MICROCONTROLLERS

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 Bogenand Vegard Wollan who designed the basic architecture at the Norwegian Institute of Technology. • RISC stands for reduced instruction setcomputer. 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)

ATMEL AVR 8 bit RISC MICROCONTROLLERS