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76  Forum 2005-2010 (read only) / Interfacing / Re: 1-wire on: October 23, 2006, 01:01:27 pm
i'd save those for a non-Arduino project, since the A/D would be wasted on it.  it's too easy to just use a cheap thermistor.  
77  Forum 2005-2010 (read only) / Interfacing / Re: 1-wire on: October 22, 2006, 12:52:17 pm
hmm, one wire?  they'd have to have two to actually do anything, and then they'd be thermistors, in which case they'd be variable resistors.

1. measure their resistance at room temperature.
2.  find a fixed resistor with that measured value (or something near it)

3. connect one between VCC and an analog-in on the Arduino
4.  connect the fixed resistor between analog-in and ground.

This makes a voltage divider based on the value of your thermistor, and the numbers from reading the analog in will have a linear relationship to temperature.  you just have to find out what that relationship is and write a function to translate.  I keep everything integer in my thermistor readings to keep things simple.  Thus 989 means 98.9 degrees Fahrenheit, etc.
78  Forum 2005-2010 (read only) / Interfacing / Re: bootloader and the parallel port programmer on: October 21, 2006, 10:41:15 am
I don't know what was going on with my parallel programmer - I resoldered it and it seems to be perfect now. Shielding and such were unnecessary. I guess I'd done a crappy solder job before.  All the those resistors are buried in epoxy now and it is perfectly reliable.
79  Forum 2005-2010 (read only) / Interfacing / bootloader and the parallel port programmer on: October 19, 2006, 09:07:47 pm
I built one of those parallel port programmers following the instructions on
and, not looking carefully, I used 470K and 220K ohm resistors instead of the ones specified.  It didn't work, of course, and then I realized I only had 560 ohm resistors, not the 470 specified.  Interestingly, this made the programmer work, but unreliably. I'd get various numbers of flash errors - sometimes as few as eight and sometimes as many as 20 depending on how close I was to 470.  Eventually I found some 470s and it works most of the time but is still unreliable. I still get flash errors - always at least two.  If I try to flash several times and end on low number of errors the bootloader usually works and I can use it in the Arduino world.

Does anyone have any ideas for how to lower the error rate?  Should I be shielding the cables or something? Should I be using ferric cores?   I have no idea what speed the data is traveling at inside the programmer, though it must be some sort of serial system.
80  Forum 2005-2010 (read only) / Frequently-Asked Questions / Re: Arduino board & stability on: January 16, 2007, 09:09:02 pm
I'm running the Arduino board continuously to control a hot water solar panel pump based on the data from several temperature sensors.  The board itself is very reliable, but occasionally the serial port hangs and needs to be disconnected and then reconnected - though this might not be the Arduino's fault.  I have, however, seen this behavior when using it with both Linux and Windows boxes.  But I'm connecting through a cheap Chinese 150 foot USB cable that I know to be unreliable in electrically noisy environments.
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