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Topic: Arduino Uno Rev3 pinouts photo (Read 94 times) previous topic - next topic

skyjumper

Dumb question... Did they change the USB interface chip and, why does its firmware need to be upgraded?

Nick Gammon

The older Uno had an Atmega8U2-MU USB interface. The Rev 3 Uno has an Atmega16U2-MU chip.

I presume the ability to upgrade the firmware is to allow for if it turns out to have some sort of bug, or maybe just for future expansion.

cyclegadget

Here is a small part of the info from this link: http://www.ladyada.net/library/arduino/unofaq.html


  The USB controller chip has moved from an atmega8u2 (8K flash) to an atmega16u2 (16K flash). This does not mean that you have more flash or RAM for your sketches this upgrade is for the USB interface chip only. In theory this will mean that it will be easier to have low level USB interfaces such as MIDI/Joystick/Keyboard available. However these are only theoretical at this time, there is no example code or firmware which will actually do this.

CrossRoads

Nick,  you didn't mention the extra pins on the power header. I think one has no connection the other is +5v also, tho not labelled that on the card.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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Nick Gammon

True, not on the photo. I mention the IOREF pin on the page I linked to.

http://www.gammon.com.au/uno

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