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Arduino Shield Odd Problem - Ideas?

  • 21-11-2013 11:27pm
    #1
    ozmo
    Registered Users, Registered Users 2 Posts: 3,888 ✭✭✭


    Shield needs a rub down before it will start :o

    Ive tried another Arduino and tried Ive tried running it without the Arduino - same thing - wont work unless you touch it to start it :confused:

    Video explains it...
    https://www.youtube.com/watch?v=hr_xC3Cyrac

    “Roll it back”



Comments

  • #2
    Johnboy1951
    Registered Users, Registered Users 2 Posts: 14,049 ✭✭✭✭Johnboy1951


    I would look for a bad connection on a pin .....


  • #3
    ozmo
    Registered Users, Registered Users 2 Posts: 3,888 ✭✭✭ozmo


    Johnboy1951 wrote: »
    I would look for a bad connection on a pin .....

    Probably - but if I touch it with a nonconductive item - pen or foam - it will not switch on. :confused:

    “Roll it back”



  • #4
    Johnboy1951
    Registered Users, Registered Users 2 Posts: 14,049 ✭✭✭✭Johnboy1951


    ozmo wrote: »
    Probably - but if I touch it with a nonconductive item - pen or foam - it will not switch on. :confused:

    Not unusual ..... touching it is not making the bad connection but causing a 'floating' pin to receive a trigger level bias which allows the start .......... that would be the theory :)


  • #5
    whizbang
    Registered Users, Registered Users 2 Posts: 1,974 ✭✭✭whizbang


    generally would look at the load/bypass capacitors for the oscillator, or crystal. I'm not sure if these things have crystals, but its common enough for crystals to have wrong capacitor values, or wrong configuration (series/paralell) selected

    The electrical noise from your finger is enough to kick it into oscillation.


  • #6
    ozmo
    Registered Users, Registered Users 2 Posts: 3,888 ✭✭✭ozmo


    whizbang wrote: »
    generally would look at the load/bypass capacitors for the oscillator, or crystal. I'm not sure if these things have crystals, but its common enough for crystals to have wrong capacitor values, or wrong configuration (series/paralell) selected

    The electrical noise from your finger is enough to kick it into oscillation.

    I think that may be it alright - lately I've found just tipping the crystal canister is enough to get it to boot.
    I was going to replace the crystal - but Ill try your suggestion first of the caps - just a little more tricky as they are surface mounted. Cheers.

    “Roll it back”



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