Arduino UNO and Mega 2560





29 thoughts on “Arduino UNO and Mega 2560

  1. They replaced the FTDI bridge with a second avr with built-in usb controller… why?
    I do understand that replacing the main MCU would have made it incompatible with previous boards but this is basically the only significant change imho. Is it worth it?

  2. Zmaster, replacing the FTDI chip with the other Atmel chip allows the Arduino to act as different USB devices if programmed to do so (input, mass storage, etc.). The FTDI chip was only for talking serial to the Arduino. If you just want to prototype things on the Arduino and then use the ATmega328 by itself then it doesn’t make any difference. If you want to use the Arduino to create devices that interface with a computer in different ways then it can make a big difference not being limited to just serial communication.

  3. The new USB interface also is much faster and has much lower latency I’m told, that should help with many projects and make new ones possible, as does the masquerading, and it’s now driverless an usable for mac and linux without issue.
    It seems quite a nice push forwards
    The only drawback might be increased cost though.

  4. @HerebusBat and Luke
    Yeah, but why 2 MCUs instead of a new smaller board with just the ATMEGA8U2?
    Why compile 2 programs and make them talk to each other when you could only use a single program on the MCU with built-in usb.

  5. One unfortunate aspect of the new board is that thought the new usb chip, the ATmega8u is easily programmable through the unpopulated ICSP header (above the chip), no other lines on the chip are available for use. You can’t even greenwire them with much ease because the chip is in a QFN package. It wouldn’t have made the board any more expensive, but infinitely more hackable, to put some unpopulated headers corresponding to the unused gpios of the ATMega8u someplace on the board.

  6. What a pity. I totally missed the atmegaXU2 series… Unfortunately they dont com in DIL packaging: I’d love to replace my favorite microcontroller (atmegaX8) with something that has real USB (not just software USB).

  7. The ATMega8u2’s are less expensive than the FTDI chips, not to mention more powerful and a smaller footprint. The ATmega8u2’s appear to also be programmable and since i heard you like Arduino’s (dawg); I put an AVR in your arduino so you can AVR while you AVR.

  8. @draeath what’s the problem with the spacing? And how mad would it be to change something so trivial and make all shields become useless, shields that sometimes can run in the hundred to purchase.

    @wiggles Really? They are cheaper? I’m surprised if that’s true, then it would make even more sense they went this route.

    @anonymous coward We’ll see what alternative versions make available, sparkfun and many others can choose a slightly different design.
    Plus I didn’t see the underside yet did you?

  9. @Mike (the other mike)

    the problem with trying to stick to a single Mega8U2 is that half the cpu time/flash space (guessing) would be lost to the USB lib’s, so it wouldnt be 100% compatible with old Mega328 apps

    best to dedicate an entire chip to the usb and let the other one run exactly the same as its always done so nothing major changes

  10. So it’s like a teensy more or less.

    I would still prefer the teensy with it’s full Speed USB connection directly to the MCU and the better price tag.

    However, all teensy boards seem to be sold out because of this new PS3-hack. Even the AVRs used in all those Boards are out of stock everywhere! Damn.

    Does anyone know where to get a teensy now ?

  11. About why 2 MCU.

    What people don’t mention here is that the Arduino board always has a replaceable ATMEga chip design. Meaning you can unplug the chip and plug in new ATMEGA328 or ATMEGA168 into it. It give lots of flexibility.

    Other thing that is totally my speculation. A nice to have feature that is not in Arduino yet is in circuit debugging. Or some way of doing that. Having 2 AVR is a move in the right direction for this. TheATMega8U2 chip is programmable and have some kind of debug wire interface. If this does not happen in Uno, perhaps in next release?

    I agree with Grenadier regarding the missed opportunity of making ATMEGA8u2 GPIO pin available on the board. In fact that will make the Uno a significant upgrade. Making ways for shield upgrade as well. Imagine having new generation shield with additional I/O pins but totally compatible with the previous hardware board. That will make Uno release an excellent reboot yet backward compatible of the platform.

    Come to think of it, this is the way to move forward. Since the ATMega328 pin out is already all exposed. The only way to upgrade is to have 2 AVR chip to give more I/O. And by realizing this suddenly the beauty of the design become apparent :D (for those who bitch about why there is two chip in there!).

    Warmest Regards!

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