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1891  Using Arduino / Networking, Protocols, and Devices / Re: Xbee on: October 24, 2012, 06:27:45 pm
And in the second sketch,
Code:
 if (Serial.read() == "D")

should be
Code:
 if (Serial.read() == 'D')

??
1892  Using Arduino / Networking, Protocols, and Devices / Re: Xbee on: October 24, 2012, 06:19:09 pm
Neither of your sketches compile for me...
1893  Using Arduino / General Electronics / Re: My 555 Tribute :( on: October 24, 2012, 01:00:13 pm
Found these the other day. Kinda cute... http://www.adafruit.com/products/1022
1894  Using Arduino / Networking, Protocols, and Devices / Re: Xbee Sereis 1 or Series 2? on: October 24, 2012, 11:21:51 am
Two devices are a network, just a minimal one smiley-grin

My $0.02 can be read here, FWIW.

If you go with S2 (now called XBee ZB), the low-power wire antenna model is a good one to start with, part number XB24-Z7WIT-004. XB24-Z7PIT-004, XB24-Z7SIT-004, XB24-Z7UIT-004 are equivalent, they just have different antenna options. The Pro models feature increased range and require significantly more power.

1895  Using Arduino / Networking, Protocols, and Devices / Re: XBEE for theatre on: October 24, 2012, 11:11:10 am

I'm thinking maybe it's an old part. What does it say on the top? Digi International or Maxstream? Still could be OK. I might try the 2xA7 firmware, but that's probably not the problem if things are working on the terminal tab.
1896  Using Arduino / Sensors / Re: FSR sensor ( counter ) problem on: October 24, 2012, 08:53:04 am
I was a bit surprised by this at first, but I get excellent results by treating an FSR exactly like a tact switch. The code below illustrates this, using a debounce library that I wrote. I have the FSR connected to A0, but it is used as a digital input; any digital or analog pin can be used. I use the AVR's internal pullup so no external resistors are required.

Code:
//Counter using a Force-Sensitive Resistor (FSR) as input.
//Connect the FSR from the designated pin to ground, with no
//pullup or pull-down resistors.
//Works with this FSR https://www.sparkfun.com/products/9376

#include <Button.h>              //http://github.com/JChristensen/Button
#define FSR_PIN A0               //connect fsr from this pin to ground
#define PULLUP true              //use the AVR's internal pullup resistor
#define INVERT true              //low level means fsr pressed
#define DEBOUNCE_TIME 50         //milliseconds

Button fsr = Button(FSR_PIN, PULLUP, INVERT, DEBOUNCE_TIME);
int counter;

void setup(void)
{
    Serial.begin(9600);
}

void loop(void)
{
    fsr.read();
    if (fsr.wasPressed()) {
        Serial.print(++counter, DEC);
        Serial.println(" steps");
    }
}
1897  Using Arduino / Networking, Protocols, and Devices / Re: XBEE for theatre on: October 24, 2012, 07:38:43 am
Note in the first pulldown on the left, I am using "XB24-ZB" as opposed to "XB24-B".
1898  Using Arduino / Networking, Protocols, and Devices / Re: XBEE for theatre on: October 24, 2012, 07:29:39 am
You do not need Series 1 modules, see my blog post on the topic here.

Having said that, I cannot find that part number on Digi's web site, although I can buy one from Mouser! I am using the XBee ZB (f.k.a. S2) modules here. Current firmware is version 2xA7.

Where did you get that module?
1899  Using Arduino / Project Guidance / Re: Long Duration Timer for Egg Incubator on: October 23, 2012, 04:20:10 pm
I'd use a real-time clock. A very accurate one that isn't too expensive and is also preassembled is the Chronodot.

Also learn to use the Time library to interface to the RTC and to trigger on those times when something needs to be done like turning the eggs.

Are you asking for someone to write the code for you?
1900  Using Arduino / Project Guidance / Re: rechargable batteries for uninterruptible power supply on: October 22, 2012, 11:01:19 pm
The test current would be limited to 20mA, which might be a bit of a light load, but it could work.

20mA?  It should not have to be more than 500 micro-amps.  The AVR specs show sample rates of 1,000 samples/sec from input impedance of 10 million ohms.  That's sample a current of just under one micro-amp at 5V.

I was thinking more from a standpoint of testing the battery with a load that approximates whatever it is intended to power.
1901  Using Arduino / Project Guidance / Re: Epileptic Siezure Alarm on: October 22, 2012, 07:50:36 pm
There are detectors for use whilst a person is in bed and hence "normally at rest" but the device required is for use during a person's normal working day.

Do you know how these detectors work, i.e. what do they sense and key on? Or can you give a link to the maker of these detectors? I know they don't cover the scenario you're interested in, but still may be a starting point.
1902  Using Arduino / Sensors / Re: MAX31855 thermocouple problems on: October 22, 2012, 05:34:45 pm
The datasheet does not recommend any capacitor across the TC leads, what's with that? I have some MAX31855s but have not tried them yet. Had very good luck with its predecessor, MAX6675.

Define "wacky"?
1903  Using Arduino / Project Guidance / Re: rechargable batteries for uninterruptible power supply on: October 22, 2012, 05:27:42 pm
You could make the ground leg of the voltage divider be an Arduino output pin.  Make it low to assert ground, take your A2D measurement, then make it an input and write a 0 to it, to turn off the pull-up.  It should not sink much current in this state.

Good idea! The test current would be limited to 20mA, which might be a bit of a light load, but it could work.
1904  Community / Bar Sport / Re: Surface Mounted Processors (Good or Bad Design?) on: October 22, 2012, 06:18:36 am
Using the DIP package makes a lot of sense on a prototyping board (read Arduino) for the reasons you list. Once I have a project fairly well settled, I'll often make a custom PC board. At that point, if space is a consideration, then a surface mount part may be the way to go.
1905  Using Arduino / General Electronics / Re: Mains Voltage and Resistors. on: October 22, 2012, 06:06:13 am
It depends. A resistive voltage divider only provides a constant voltage if the load that it is connected to draws a constant current. It has to be designed with a specific load in mind. If whatever the Arduino is doing results in it using a relatively constant current then it could work. But it might not work well for another Arduino project that has different current requirements.

It's a poor design for a power supply. So poor that it can hardly be called a power supply. Even a Zener diode would be preferable. Attempting such stunts will result in your EE friends laughing at you.
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