AVR risc microcontrollers from Atmel
The following documents are big PDF files.
I encourage you to download them and use a PDF viewer to study them.
At this point in time, firefox (and perhaps other browsers) have a minimal
built in PDF viewer, but it does not provide the table of contents
along the left side, wich is almost indispensible when working with a 400 page document.
First, some documents that pertain to AVR parts in general:
The devices used in Arduinos are "megaAVR" family parts:
The newer series of AVR chips have onboard USB:
- ATmega8 16 Mhz, 8K flash, 1K SRAM, 0.5K EEPROM, 6 or 8 channel 10 bit ADC, 23 IO pins.
- ATmega168 20 Mhz, 16K flash, 1K SRAM, 0.5K EEPROM, 8 channel 10 bit ADC, 23 IO pins.
datasheet (378 pages, pdf)
- ATmega328P 20 Mhz, 32K flash, 2K SRAM, 1K EEPROM, 8 channel 10 bit ADC, 23 IO pins.
datasheet (419 pages, pdf)
- AT90USB1286 16 Mhz, 128K flash, 8K SRAM, 4K EEPROM, 8 channel 10 bit ADC, 46 IO pins.
datasheet (456 pages, pdf)
The one glaring limitation in all of these chips is very little SRAM.
In all but the 90USB1286 there is only enough to hold the execution stack and a few variables.
Exactly what AVR stands for is uncertain and sometimes debated.
The most likely truth is that
AVR stands for Alf (Egil Bogen) and Vegard (Wollan)'s Risc processor.
These guys were the chip designers, and designed the chip while students
and working at Nordic VLSI (now Nordic Semiconductor) in Trondheim, Norway.
The design was later sold to Atmel.
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Tom's Computer Info / email@example.com