Category Archives: AVR Microcontrollers

AVR Microcontroller Default Clock

One feature of AVR devices that can baffle new users is the default clock setting on new AVR microcontrollers. They are set to run from their internal RC oscillator, usually 1 MHz, which throws out the timing on code samples, such as UART.

If the code is configured for an 8MHz clock and there is a 8MHz clock on the target board, you expect it to work but instead you get nothing or garbled characters. This is due to the default Internal RC. How do you change it?

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AVR Microcontroller C Code

The AVR microcontroller is excellent with C code because it was designed with C in mind. Atmel have also made it easy to use C in AVR Studio, as WinAVR compiler can run from within AVRStudio just like the assembler.

Only a few years ago, using C compilers involved complicated commandline instructions and make files but WinAVR more or less takes care of this for you. WinAVR is based on the free GNU-GCC compiler but is much friendlier, especially for beginners.

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AVR Microcontroller Coding

The question we are often asked is should I start with C or assembly language to program my AVR microcontroller? Well, there are pros and cons to both approaches.

C has many advantages, including much faster code writing and increased portability. It is also much easier to understand and modify the code later. By using library files, code can be reused easily or pre-written functions can just be added by including a library.
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AVR Microcontrollers

AVR microcontrollers were made by Atmel but Atmel have now been taken over by Microchip, who make the PIC microcontroller as well. They are available from Microchip directly, from any of their distributors or here on the Kanda site.

The range covers everything from 1KB 8-pin devices to 100-pin 256KB microcontrollers.  Available package types include DIP, SOIC, QFN and TQFP. They feature all the usual peripherals including UART, SPI and Two Wire Interfaces, plus ADC,  analog comparators and PWM for analog work and some have more advanced features like CAN and USB.
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