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Member Since: April 22, 2011

Country: United States

    I can't for the life of me work out how nobody has reported this?
    On my MPL115A1 device, when the temperature goes over 25 degrees c, the computeTemperature() function in all Arduino examples I have found) returns a negative temperature like "-12222.4 degrees. (and some people can't understand why I hate 'C').
    The offending code is the last line of that function, where it computes the return value:
    return 25 + (uiTadc - 472) / -5.35;
    The error occurs because the Arduino processes 'part' of the above using integer arithmetic and when the ADC crosses the 472 constant the 'sign' inverts. The compiler is probably getting confused because 'uiTadc' is an unsigned int.
    THE FIX: Simply add a ".0" (decimal point zero) after the 472 constant, this forces it to be computed as a float, so that when we multiply it by '-5.35', 'C' doesn't choke on it and sprurt out it's breakfast. I also added additional brackets as shown below, though probably not needed.
    return 25 + ((uiTadc - 472.0) / -5.35);
    Once I did that, I got more stable results when below 25c and correct (i.e. positive) results above 25c.
    I found I needed to tweak the function to improve the accuracy. I calibrated it by printing out the ADC count (uiTadc) at two known temperatures, and with a simple Excel spreadsheet, I found the following was perfect for my chip:
    return 25 + ((uiTadc - 498.0) / -5.35);
    I'm running this on a Mega-2560, there may possibly be a bug in the Mega core which might explain why nobody has reported this already?
    Hope this saves somebody from ripping out their last few sprigs of hair, like I did!!!
    Paul Taylor {Affordable Technology - Perth}

  • The manufacture of "Warning Labels" MUST be the fastest growth industry in America? Just a thought...
    FOR SAKE, this product is just an insulated piece of wire, with exposed metal on both ends.
    Let's face it, the idiots that a number of you are worried about, will NOT spend $7 on contacts and a socket for their 'DIY taser' they are building from an old electric fence box they found on uncle Bill's farm!!!
    We all know our idiot will simply tackle Billy-Bob to the ground and connect the new 'toy' to his nipples* with the battery jumper cables from the tractor. After all, the whole purpose is to see if he can get Billy-Bob to twitch hard enough to do a full 360 degree somersault. Them flimsy little leads are no where near as appealing as hefty 60 Amp jumper cables.
    *-forgive me for saying 'Nipples', I was being polite. We know the 'probes' will probably be clamped further south of the border.-.
    P.S. Idiots wont spend money on a quality product, they will make their own from tin-foil and jumper cables etc - These decent contact pads will be purchased by people who want to do things properly - and carefully!

    P.S.S. Idiots don't read warning labels either!

    Now, for those who are looking forward to using these probes for real projects:
    | Post by Austipodean | July 10, 2011
    | with a link to SiliconChip Magazine's
    | nerve stimulation circuit.
    If you didn't get a kick from that link, this one's a guaranteed screamer.

    Don't forget, before testing a new project yourself, always paint your name across your chest, so the 'Darwin Awards' people don't spell it wrong!

    Anyhow, must run, I just getting the kinks and final wrinkles out of my "Electronic Viagra" project - watch out for it in SparkFun's 'Featured New Product' list in 3 or 4 weeks.

    It is my opinion that the PCB differs from the circuit diagram on a critical point.
    The 'Power Target' switch (on my board) is NOT wired as per the diagram. It removes VCC from both the ISP connector AND the 74LC125 buffer IC.
    This means that your target device still gets 5 Volts via an internal path through the 74LC125.
    No big deal, except if you plug in a target which uses 3 Volts only.
    My $50 Seeeduino Film was instantly destroyed!!! Not very happy at all.....

  • Hmmm,
    I dunno, but description clearly states:
    "Supports up to 32 user-defined Speaker Dependent (SD) triggers or commands (any language)"
    So maybe, if the "sound" that you want to activate a command with, happens to be similar to the sound of ANY word, in ANY language, as spoken by ANY individual - it will work!!!
    Don't forget it also works with ALL known (and unknown) inter-galactic languages as well. So if it is an unusual sound that you need to work, I'd bet you'd find a sufficiently close match in Klingon.
    Best plan is to send an audio tape of your sounds of interest, to the The Klingon Language Institute and they will be able to tell you immediately if any are close to official Klingon words.
    Otherwise, there is an on-line English / Klingon translator which gives pronunciation as well.
    Good luck with the project, I hope you find what you really need!