AVR microcontrollers: Difference between revisions

Revision as of 07:35, 10 April 2005

Revision as of 18:13, 10 April 2005

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The AVR was designed at the outset for efficient execution of [[compiler|compiled]] [[C programming language|C]] code. Thus some instructions, such as '<code>add immediate</code>', are strangely missing (you have to '<code>subtract immediate</code>' the [[complement]] instead), while others, such as '<code>compare with carry</code>', are included.

The AVR instruction set is physically implemented and sold on the market as a bunchnumber of different controllers, sharing the same AVR core but differing on peripheral / RAM / ROM capabilities: from the Tiny AVR controllers with 1KB flash ROM, no RAM, and 8 pins, up to Mega AVR controllers with 128KB flash ROM, 4KB RAM, 4KB EEPROM, 10 bit ADC with 8 channels, timers, comparators, JTAG, etc. Compatibility across models is preserved. <br>to a reasonable degree.

Atmel's AVR controllers have a pipeline with 2 stages (fetch and execute) that allows them to execute most instructions in 1 clock, which makes them relatively fast among the 8-bit controllers on the market.