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1  Using Arduino / Project Guidance / Re: Controlling car fuel gauge on: Today at 03:32:07 pm
Another way to determine what the gage is actually measuring is to put the gage in series with a 30-Ohm resistor and measure the current through the pair.  That should tell you the internal resistance of the gage. 

An NPN transistor driven by PWM ought to let you adjust the average current through the gage to let you display values.
2  Using Arduino / General Electronics / Re: Storing Arduino and other hardware on: Today at 03:18:11 pm
I like the Plano Molding model 3750 "StowAway Utility Box" for Arduino stuff:

http://www.planomolding.com/product.php?BCCID=136&PID=953

I got mine in the Crafts section of Walmart.  I think Walmart sells them under the brand "Creative Options" but I can't find the exact match at the Walmart website.  If I recall correctly they were only about $6.
3  Topics / Robotics / Re: Connecting Arduino to Servos and Rotary Switch on: Today at 11:33:09 am
The "rotery" switch isn't a rotary switch.  It's a microswitch like those used as limit switches in mechanical equipment.  It looks like there is one on each of the front corners to detect wall collisions.
4  Using Arduino / Sensors / Re: Arduino kit project 3 light sensor on: Today at 11:01:37 am
Sounds like a wiring error.  Double-check your connections. 

One issue that catches some people is that some larger breadboards have power rails that are split half way.

What numbers are you getting?
5  Using Arduino / Networking, Protocols, and Devices / Re: I need typical example "activating led" through web but the UIPEthernet library on: Today at 10:57:09 am
I have a rookie question, I am newbie with arduino, normally  I can find the code to run my program,  but I've found a little problem that I can not fix (sure is very easy), I can not find a typical example of activating led through web but with the UIPEthernet  library .

Could you show me a basic example with your library?

The website (https://github.com/ntruchsess/arduino_uip) says:
"UIPEthernet: A plugin-replacement of the stock Arduino Ethernet library for ENC28J60 shields and breakout boards. Full support for persistent (streaming) TCP-connections and UDP (Client and Server each), ARP, ICMP, DHCP and DNS. Build around Adam Dunkels uIP Stack."

From that it looks like any examples you can find for the Arduino Ethernet Library should work with the UIPEthernet Library.
6  Using Arduino / Networking, Protocols, and Devices / Re: Issue with serial communication on: Today at 10:50:34 am
Code:
  Serial.print("ADR 06" + '\r' + '\n');

I'm pretty sure that doesn't do what you intend it to do.  You can't concatenate character constants to a character string constant with the addition operator.

You should try:
Code:
  Serial.print("ADR 06\r\n");

This will also work but makes it less readable:
Code:
  Serial.print("ADR 06"  "\r"  "\n");  // Adjacent string constants are merged
7  Using Arduino / Project Guidance / Re: Controlling car fuel gauge on: Today at 10:29:58 am
From the KUS website:
American standard:  240 ohm at empty, 30 ohms at full
European standard: 0 ohms empty, 180 ohms at full

The gage is measuring the voltage drop across the sender or the voltage drop across an internal resistor.  They say "Connect to 12 Volt directly. If you have 24 volt system you must use the added resistors as shown in the diagram. " without showing the diagram.  If you can find the diagram then it should be fairly easy to determine what quantity the meter is measuring.
8  Using Arduino / Motors, Mechanics, and Power / Re: Spectrum Linear servo. on: Today at 10:10:25 am
The servo is very small and lightweight so I doubt it draws a massive current. I have checked the voltage of the 3.3 pin and it doesn't alter when I plug in the servo so I think it's ok.

I'm sure it draws very little current, until you try to spin the motor. smiley
9  Using Arduino / Programming Questions / Re: Alternative pulse width measurement. on: Today at 10:04:24 am
You could use a single interrupt set for CHANGE.  That will interrupt on both edges.  You can check the state of the pin to see which edge just occurred (HIGH->RISING or LOW->FALLING) .  Use the micros() function to get the time in microseconds.

The Timer/Counter 1 has an Input Capture feature which can store the current timer count when the Input Capture pin changes.  That might give you a hardware way to time pulses to 1/8th of a microsecond.  The Input Capture interrupt can be set for a Rising edge at which time you can grab the timer value and change it to a Falling edge.  When the falling edge interrupt occurs you can subtract the old time from the new time to get the pulse length.  Then set the edge back to Rising.  This will use very little CPU time and should give accurate results regardless of interrupt latency.
10  Using Arduino / Networking, Protocols, and Devices / Re: UART FF only on: Today at 09:43:32 am
everything I call serial#.read() it returns FF.

Serial#.read() returns an int.  The value is -1 (0xFFFF) if there is nothing in the buffer. If you store that in an unsigned char it will get truncated to 0xFF.

Show your code.
11  Using Arduino / LEDs and Multiplexing / Re: Reading LEDR-L-7113ID-12V datasheet on: Today at 09:38:28 am
The datasheet says: "12V internal resistor." so the LED package already contains the series resistor to limit the current to a safe level when 12V is applied.  The calculations for what resistor to use assumes a bare LED with no internal resistor.  Does the starter kit not come with any plain LEDs?
12  Using Arduino / Project Guidance / Re: PID Control Library Question on: Today at 09:27:47 am
You could read the documentation:

http://playground.arduino.cc/Code/PIDLibrarySetControllerDirection
"Direction: DIRECT (like a car) or REVERSE (like a refrigerator)"

DIRECT:  If the Input is above the Setpoint, the Output goes LOWER.
If the speed of the car is above the desired speed set the throttle point lower.

REVERSE: If the Input is above the Setpoint the Output goes HIGHER.
If the temperature of the refrigerator is above the desired temperature, turn on the compressor more often or longer to bring the temperature down.
13  Using Arduino / Sensors / Re: Unable to compile sketch for multiple sensors on: Today at 09:20:19 am
SONAR_NUM is not a compile-time constant so you can't use it to declare the sonar array.

Looks like you are declaring local variables in setup() and then trying to use them as global variables.

Dividing by an uninitialized variable (US_ROUNDTRIP_CM) is a sure way to get the wrong answer:

Code:
void echoCheck() { // If ping received, set the sensor distance to array.
  int CM[3];
  int US_ROUNDTRIP_CM;

  if (sonar[currentSensor].check_timer())
    cm[currentSensor] = sonar[currentSensor].ping_result / US_ROUNDTRIP_CM;
}
14  Topics / Home Automation and Networked Objects / Re: New To arduino - looking for guidance on a project on: Today at 09:02:27 am
"PoE" is "Power over Ethernet".  It is a standard for using spare wires on the Ethernet cable to provide DC power to remote Ethernet devices that are not near an AC outlet.  Some Ethernet routers are capable of providing PoE on some or all of their ports and if your router doesn't provide PoE you can use a power injector to add power to the cable after it leaves the router.

Were you planning to run AC and Ethernet to every Smart Outlet?
15  Using Arduino / Installation & Troubleshooting / Re: ArduinoToBreadboard tutorial workaround? on: Today at 08:52:24 am
To use the ArduinoISP sketch on an Arduino UNO you need to disable the UNO's Auto Reset after you upload the ArduinoISP sketch.  Connect a 1 to 10 uF capacitor between the UNO's Reset pin (+) and Ground pin (-).

Note that if the ATmega328p chip is not fresh from the factory, for instance if it ever has an Arduino bootloader burned, it may need the crystal in order to be programmed.  The serial programming uses the system clock and a chip configured to use a crystal won't have a working system clock if the crystal isn't present.
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