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31  Using Arduino / Motors, Mechanics, and Power / Re: how to use the MG995 360dgrs ? on: September 16, 2014, 11:16:25 am
What you have bought is a servo modified for "continuous rotation".   It is no longer a servo that can be directed to a particular position: it is a gear-motor with a speed control.  Send it a pulse near 1500 microseconds to stop.  Lower values (down to about 1000 uS) turn one way and higher values (up to about 2000 uS) turn the other way.

If you want a servo that you can point in any direction you probably want a multi-turn sail winch servo like this 4-turn model:
32  Using Arduino / Audio / Re: Using more than 16 analog inputs for a MIDI controller on: September 16, 2014, 11:05:35 am
Analog multiplexers will let you connect 8 or 16 analog inputs to EACH analog input of the Arduino.  You can buy a Mux Shield II which allows 48 analog inputs:
33  Development / Other Hardware Development / Re: where i can buy a stepper motor gear like this on: September 16, 2014, 10:58:32 am
A blurry picture of one side of a gear is not sufficient.  You need to determine the specifications of the gear:  tooth count, pitch, pitch angle, width (total and just the geared part)...  Take the gear to a gear distributor and ask them for a matching gear.
34  Using Arduino / Programming Questions / Re: Mapping analog inputs - not working as expected on: September 16, 2014, 09:48:44 am
If you want the LED to stay on some you should not dim all the way to 255.  I think that instead of the range 255-50 (off to fairly bright) you intended the range 205-0 (dim to full bright).
35  Using Arduino / Project Guidance / Re: Controlling car fuel gauge on: September 15, 2014, 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.
36  Using Arduino / General Electronics / Re: Storing Arduino and other hardware on: September 15, 2014, 03:18:11 pm
I like the Plano Molding model 3750 "StowAway Utility Box" for Arduino stuff:

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.
37  Topics / Robotics / Re: Connecting Arduino to Servos and Rotary Switch on: September 15, 2014, 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.
38  Using Arduino / Sensors / Re: Arduino kit project 3 light sensor on: September 15, 2014, 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?
39  Using Arduino / Networking, Protocols, and Devices / Re: I need typical example "activating led" through web but the UIPEthernet library on: September 15, 2014, 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 ( 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.
40  Using Arduino / Networking, Protocols, and Devices / Re: Issue with serial communication on: September 15, 2014, 10:50:34 am
  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:
  Serial.print("ADR 06\r\n");

This will also work but makes it less readable:
  Serial.print("ADR 06"  "\r"  "\n");  // Adjacent string constants are merged
41  Using Arduino / Project Guidance / Re: Controlling car fuel gauge on: September 15, 2014, 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.
42  Using Arduino / Motors, Mechanics, and Power / Re: Spectrum Linear servo. on: September 15, 2014, 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
43  Using Arduino / Programming Questions / Re: Alternative pulse width measurement. on: September 15, 2014, 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.
44  Using Arduino / Networking, Protocols, and Devices / Re: UART FF only on: September 15, 2014, 09:43:32 am
everything I call it returns FF. 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.
45  Using Arduino / LEDs and Multiplexing / Re: Reading LEDR-L-7113ID-12V datasheet on: September 15, 2014, 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?
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