AVR quick start

==Features==

==Development and programming==
===IDE and compiler===
One of the super nice things about the AVR are the totally open source tools.
*[http://winavr.sourceforge.net/ WinAVR and GCC] (GPL)
*Atmel's [http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2725 AVR Studio 4] (Windows Only, registration required, uses avr-gcc)
*[http://www.obdev.at/products/crosspack/ CrossPack] similar to WinAVR but for Mac OS X.

===Programmers===

Typically AVR programming can be done with the normal circuit voltage 5 V or 3.3V, which allows many different low cost options for getting started with AVRs.  The open source and multi-platform [[AVRDUDE_AVR_programmer|AVRDude (AVR Downloader Uploader)]] utility is commonly used for programming AVRs.  AVRDude is included in some of the AVR IDEs such as WinAVR and Arduino.  AVRDude supports using the [[Bus Pirate]] as an AVR programmer since release 5.8.
*[[Bus Pirate AVR Programming]] - The Bus Pirate can be used as an AVR programmer with AVRDude, eliminating the need for a separate AVR hardware programmer.  Note: some older versions of the Bus Pirate firmware are incompatible with AVRDude.
*[http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2735 Atmel STK500 programmer].  Many clones are available.
** ([[Bus_Pirate#WinAVR|Bus Pirate as an STK500 clone ]]) - Using an alternate firmware on the Bus Pirate, it can emulate the STK500 programmer.  Use this if you require compatibility with some AVR programming software other than AVRdude.  Recent versions AVRDude can be use the Bus Pirate directly with the default Bus Pirate firmware.  a
*AVR ISP (and [http://www.adafruit.com/index.php?main_page=product_info&cPath=16&products_id=46 kits])
** [http://arduino.cc/en/Tutorial/ArduinoISP ArduinoISP] The Arduino can be used as an AVR ISP programmer after loading the ArduinoISP sketch.
*FTDI Bit Banging - The popular FTDI USB to RS-232 chip can be used for [[wikipedia:bit-banging|bit-banging]].  See [http://hackaday.com/2009/09/22/introduction-to-ftdi-bitbang-mode/ Hack-a-day Introduction to FTDI Bit-bang Mode].  It's possible to use an FTDI converter with 5V or 3.3V outputs to program AVRs.  This can be one of the slower ways to program AVRs however many people have FTDI converters lying around.
** Dangerous Prototypes has an [[FT232 programmer]] in development.
** FTDI USB serial TTL converters are available in many forms from FTDI, SeeedStudio, etc.
** It's possible to use the FTDI chip on some Arduino's such as the Duemillanove and clones.
*MKII (full AVR debugger)
*Mega-ISP Arduino shield
AVRs also have an alternate 7-pin programming mode that requires a 13volt supply. This mode is usually only needed to enable/disable the RESET pin. Very few programmers support this mode.
*[http://mightyohm.com/blog/2008/09/arduino-based-avr-high-voltage-programmer/ AVR HVP Arduino shield]

===Bootloaders===
AVRs do not ship with a bootloader, but there are many that you can program yourself. After the bootloader is installed, a programmer is no longer needed for simple firmware updates.
* [http://www.arduino.cc/en/Main/Bootloader Arduino Bootloader]
* [http://www.avrfreaks.net/index.php?module=Freaks%20Academy&func=viewItem&item_type=project&item_id=1008 fast tiny & mega UART bootloader] (registration required) (license?)
* [http://sourceforge.net/projects/kavr/ kavr] (GPL)
* [http://www.fourwalledcubicle.com/LUFA.php LUFA] (MIT Licensed) contains USB bootloaders for the following USB classes:
** CDC Class, AVR109 protocol compatible ([http://www.nongnu.org/avrdude/ AVRDude])
** DFU Class, Atmel DFU protocol compatible ([http://www.atmel.com/dyn/products/tools_card.asp?tool_id=3886 Atmel FLIP], [http://dfu-programmer.sourceforge.net/ dfu-programmer])

==Basic circuit==
[[Image:Quick-avr-basic.png|Basic AVR circuit|490px]]
===Power===
*Connect all the supply pins to power (Vcc) or ground (Vss). Don't forget the AVcc and AVss pins
*Put a 0.1uF decoupling capacitor on each positive supply pin, and put it as close to the chip on your PCB as possible

===Reset===
*Reset is the RESET pin on AVRs
*Connect a resistor from RESET to the supply voltage for normal operation. Any value between 1K and 10K ohms should work fine
===Programming connections===
Most AVRs use a 6 or 10 pin programming connection called ISP (in system programming).

[[Image:Qucik-avr-ISPconnector.png|AVR ISP Connectors (Top View)]]
{| class="wikitable" border="1"
|+ ISP Connector pinout
! Signal !! 6-Pin !! 10-Pin !! I/O !! Description
|-
| VTG || 2 || 2 || - || Power is delivered from the target board (?)
|-
| GND || 6 || 3,4,6,8,10 || - || Ground
|-
| MOSI || 4 || 1 || Output || Commands and data from Programmer to target AVR
|-
| MISO || 1 || 9 || Input || Data from target AVR to Programmer
|-
| SCK || 3 || 7 || Output || Serial Clock, Controlled by Programmer
|-
| RESET || 5 || 5 || Output || Reset. Controlled by Programmer
|}

===Clock source===
Most AVR's have an internal RC oscillator, clocked at 8Mhz, that can be used as the clock source. By default the Clock divider fuse (CKDIV8) is programmed, resulting in a 1Mhz clock.
*An external clock source, resonator, or crystal can be attached to the XTAL1 (input) and XTAL2 pins.

==Peripherals==
===IO===
*General guide to PORT current limits
===USB===
*Basic AVR USB circuit requirements
*USB supply
*Any components needed for the USB PHY


[[Category:Tutorials]]
[[Category:Processor Overviews]]
[[Category:AVR]]