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Arduino Mega ATmega2560 standart is missing cpu pins to headers :o)

Discussion in 'Arduino' started by voidptr, Feb 19, 2013.

  1. voidptr

    voidptr Member

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  2. misterT

    misterT Well-Known Member Most Helpful Member

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    What features can't you use with the arduino?

    Arduino has 56 IO pins on headers. The Seeduino has 70 IO pins, but costs 20 dollars more.. other than that they are the same.

    Can't see why would it be so horrible to leave out a few IO pins in order to keep the board compatible with all the shields available. Do you really need all 70 IO pins?
     
  3. voidptr

    voidptr Member

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    I cant see why they(the official guys) did not want to, at least, bring those pins to an nonstandard headers !?!?!?

    anyway when I started one of my current projects, I read the mega2560 doc and found it will fit nicely with all 6 timers/ counter ...

    I wanted basically using 2 16 bits counters for external events (timer 4 and 5 external counter with hardware interrupt latching)
    and 2 others for PWM , and others for the usual arduino stuff ( ms delay etc ..)

    I was badly surprise to find that not all pins of timers were connected ...

    So I told myself WTF are they doing!!!

    And found that Seeed had build a correct board with all pin routed !

    So for blinking leds the official board is fine , but not if you want to use all timers !

    :p

    PS BTW one of my friend was not really lucky with the real cheap ebay version at $20 (board had crappy soldering on it)...
    so paying a bit more (but still less than the official one) for a good board quality is not so bad !
     
    Last edited: Feb 19, 2013
  4. dave

    Dave New Member

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  5. misterT

    misterT Well-Known Member Most Helpful Member

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    Well, yeah. Two of the four "input capture units" are not connected to any headers. But still there should be two available (Arduino pins 49 and 48).. also plenty of PWM channels available (at least seven). And you don't need any output pins if you use a timer for "usual arduino stuff like delays".

    Anyway. The Seeduino looks like a nice simple board. At least it has some space around the mounting holes. The holes in Arduino are almost useless because they are too close to the headers.
     
    Last edited: Feb 20, 2013
  6. Rich D.

    Rich D. Member

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    "The holes in Arduino are almost useless because they are too close to the headers."

    Amen to that!
    They may have a great marketing machine but they made some pretty dumb design decisions.
    Board Layout 101: Step 1. Add mounting holes.

    And what's with that .06" connector offset?! Don't they ever use perf-boards in Italy?!
     
  7. ADWSystems

    ADWSystems Member

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    Amen to that!

    If there wasn't the 0.060" offset the screw head/nut/standoff might actually fit.

    I'm designing a few of my own shields now. I know that mounting holes stink but they are necessary. A #4 nut requires almost 0.250" circular pad. That is a lot of real estate but you have to mount it some how.
     
  8. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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