Atmel AVR Jared Bevis January 14, 2008

The Power of Your Chips The main power of your chips lies in the programming language/compiler available to you. – C is very powerful for both high and low level designs. – BASIC is very easy to learn for beginners, however you are at the mercy of the compiler and built in functions of the language.

BASIC – Has a large variety of functions built in for the PIC including: Digital to Analog conversion Analog to Digital conversion Software UARTS LCD Support Many others – Has very big limitations: No floating point number support. Very hard to change built in functions.

C – Does not have many “built in functions” This is easily overcome as you build your own code libraries. – Common libraries will be provided in demos » LCD Code written by me » ADC Code written by me – Very flexible Functions can quickly be written or modified for project specific purposes. Supports advanced arithmetic – Floating numbers – Trig functions – Array support

AVR Features AVR series come in both 32 and 8 bit architectures. Shares many features with the PIC such as ADCs, UARTs, SPI, I2C, pin pull ups, interrupt on pin changes, etc. Additional feature not present in PICs is sixteen bit PWM channels (generally three per 16 bit timer). – VERY useful for servo motor applications AVR chips offer single cycle instructions; the PICs require four clock cycles for each instruction.

Gotcha’s for Each Chip The PIC has many auxiliary functions of pins turned on by default such as comparators or PWM channels which must be manually turned off for certain compilers to enable normal I/O functions. The Atmel AVR has fuse settings which must be written into the device. If settings are incorrect for your application, you may render the chip useless.

AVR Software The AVR software is written by the manufacturer Atmel. AVR Studio is available for free download. – Natively supports assembly programming. Companion software to AVR Studio is WinAVR. – Provides a C compiler for AVR Studio. AVR Studio projects are easily written in C and integrate well with WinAVR for compilation.

Both pieces of software are provided free without licensing hassles or royalty fees. – Download AVR Studio from – Download WinAVR from ge_id= ge_id=66543 Be sure to install AVR Studio before installing WinAVR.

Programming Hardware Hardware is relatively cheap ~$35-$40 – With school discount Atmel is about $17 – Highly recommend buying your own whether you choose to use PIC or Atmel (programmers are NOT allowed to be taken outside of lab): PIC programmer is Pickit2 AVR programmer is AVRISP mkII – Both these programmers will program your chips in circuit using about five pins. See documentation for connection info.