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1  Using Arduino / Programming Questions / Re: How to do one program with two program in arduino ? on: Today at 09:32:04 am
http://www.thebox.myzen.co.uk/Tutorial/Merging_Code.html
2  Using Arduino / General Electronics / Re: Voltage trigger on: Today at 07:55:59 am
Use a resistor voltage divider to reduce the 12V to 4 to 4.5V.  Measure the 12V to make sure that it is indeed 12V (not higher) and use the measured voltage in the voltage divider calculation.  Connect the center of the voltage divider to a digital input.  When the 12V comes on there will be 4-4.5V at the pin.  If(digital_input == HIGH) send SMS.

http://www.daycounter.com/Calculators/Voltage-Divider-Calculator.phtml
3  Using Arduino / General Electronics / Re: How do I replace a moral rectifier part? on: April 17, 2014, 11:58:22 am
AdaFlute has a moral bridge that may be an indirect replacement.
4  Using Arduino / Project Guidance / Re: Serial commands from computer through arduino to another device on: April 17, 2014, 10:44:59 am
Quote
Bad information that is becoming a forum urban legend, probably because many don't understand the TTL operations. The arduino can send tx to a large number of rx, and the arduino can receive rx from a large numbet of tx if each tx has a properly aligned diode in the tx line.

Zoomkat.  My bad then.  This is the first that I have heard of this and would like to know more about the technique.  Would one also need a protocol to identify the sender and/ or receiver?
5  Using Arduino / Sensors / Re: Using two Ultrasonic Sensors HC-SR04 on: April 17, 2014, 10:35:52 am
http://forum.arduino.cc/index.php?topic=145816.0
6  Using Arduino / Sensors / Re: MPU 9150 compass data reading -1 on: April 17, 2014, 10:24:26 am
The first ting that I would do is run the I2C Scanner (by Nick Gammon) to make sure of the device address and that  it's communicating with the bus.

Code:
#include <Wire.h>

void setup() {
  Serial.begin (115200);

  // Leonardo: wait for serial port to connect
  while (!Serial)
    {
    }

  Serial.println ();
  Serial.println ("I2C scanner. Scanning ...");
  byte count = 0;
 
  Wire.begin();
  for (byte i = 1; i < 120; i++)
  {
    Wire.beginTransmission (i);
    if (Wire.endTransmission () == 0)
      {
      Serial.print ("Found address: ");
      Serial.print (i, DEC);
      Serial.print (" (0x");
      Serial.print (i, HEX);
      Serial.println (")");
      count++;
      delay (1);  // maybe unneeded?
      } // end of good response
  } // end of for loop
  Serial.println ("Done.");
  Serial.print ("Found ");
  Serial.print (count, DEC);
  Serial.println (" device(s).");
}  // end of setup

void loop() {}
7  Using Arduino / Programming Questions / Re: Strange behaviour using interrupts on: April 17, 2014, 09:26:57 am
Can you elaborate?  Not working as expected in what way?  Interrupt fires when button released?
8  Using Arduino / Programming Questions / Re: Strange behaviour using interrupts on: April 17, 2014, 09:09:37 am
Do you have any debounce on the switch?  The switch bounce will trigger multiple interrupts. How is the switch wired?  Attached is the more accepted way to wire a switch.  This way allows hardware debounce and the use of the internal pullup.  If hardware debounce is not enough, you can add debounce in software.
9  Using Arduino / Project Guidance / Re: Serial commands from computer through arduino to another device on: April 17, 2014, 08:55:02 am
Yes, that's it.  You don't say which Arduino.  i only know the Uno (mega328).  If you have a Uno, and are connected via USB then you are using pins 0 and 1 which are the hardware serial port pins.  So set up a software serial port, on 2 different pins, and connect that to the other device.  You can then send and receive from the other device, have the Arduino act on received data and relay to the PC.
10  Using Arduino / Project Guidance / Re: Serial commands from computer through arduino to another device on: April 17, 2014, 08:40:07 am
If you are using the hardware serial (pins 0, 1) to communicate with the PC you can't also use it the connect with another device.  Use Software Serial library (comes with the IDE) on 2 other pins to connect with the other device.  Monitor the software serial port for the trigger byte.
11  Using Arduino / Sensors / Re: Photo Interrupter Sensor Questions on: April 17, 2014, 07:45:34 am
To calculate voltage from raw ADC counts you need to know the value of the analog reference voltage and the ADC resolution.  On a Uno, using the default reference, the reference voltage is the supply voltage (around 5V) and resolution is 10 bits.  So the formula to calculate voltage (for Uno) is ADC counts * (Vref/1024). 
The numbers shown should work with a digital input.
12  Using Arduino / Project Guidance / Re: I need help with a project. on: April 16, 2014, 07:59:47 pm
In the IDE there is an example called "blink without delay".  Go to File, Examples, Digital.  The example uses millis() to control timing without "blocking" or stopping the program.
13  Using Arduino / General Electronics / Re: Help: How to connect many buttons on the bread board on: April 16, 2014, 07:31:26 am
I could not open the video as it is private.  It may be, from your description, that the horizontal (power rails) are split in the middle and require a jumper to connect them.  many breadboards are built that way.
14  Using Arduino / Displays / Re: Displaying a picture in LCD using arduino? on: April 15, 2014, 11:52:37 am
Depends on the image and the LCD.  You need to be way more specific.
15  Using Arduino / Project Guidance / Re: Possible to use photoresistors as digital in? on: April 15, 2014, 07:55:33 am
You could use a LM 339 quad comparator to condition the signal from the photo resistors and also set a threshold for the switching.   By varying the reference voltage at the comparator you can adjust  the voltage level (light strength) that switching takes place.  A Schmitt trigger will have a fixed trip point.
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