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1  Using Arduino / Sensors / Re: OpAmp shield on: January 22, 2013, 11:30:29 am

This does not allow you to adjust the offset or the gain though...
2  Using Arduino / Sensors / Re: OpAmp shield on: January 22, 2013, 11:29:40 am
Well its easier than route your own and to then get it produced, especially for a mechanical engineer:)
3  Using Arduino / Sensors / OpAmp shield on: January 22, 2013, 04:19:28 am
I am looking for an OpAmp shield so I can attach my strain gauge to. I have tried google, but I have problem finding one, ideally I would like to have at least 4 OpAmp on one shield. Does anyone knows if such a shield exist?

4  Using Arduino / Sensors / Re: Arduino setup with heaps of sensors/Paternoster on: November 19, 2012, 07:56:20 am
Ok, but should i have 5 or 1 arduino? and which connectors to use and cable dimmension?
5  Using Arduino / Sensors / Re: Arduino setup with heaps of sensors/Paternoster on: November 18, 2012, 05:17:41 pm
Havent decided on any sensors yet, just figured out which sensors that i need. I just need to have some kind of current sensor to figure out if there is a mechanical jaming that avoids my motor to run properly.
6  Using Arduino / Sensors / Arduino setup with heaps of sensors/Paternoster on: November 18, 2012, 03:48:46 pm
I have question regarding cabling and how many arduinos to use.
I have a plate with 4 sensor units, 1 on each corner. The plate has the dimension of 400x1200mm, but it might change in the future. The sensor units in front differs to the ones in back by that they have one extra motor, current sensor and voltage sensor and the two in back do have an extra potentiometer. The motor could peak out at 30Ampere @ 12v, however only one motor per unit will be running at maximum current at the same time, i.e total consumption = 30A.
On the front units I have 3+2=5 IO +   2+2=4 analog inputs and 2 interupts
The back units 3+1 = 4IO + 1+1+1=3 analog inputs and 2 interupts

The control hub has 4 analog input and needs to communicate with an android tablet, so I guess arduino leaonard will be perfect for this. The question is how to get the 4 sensor units to communicate with the control hub. Should I put one arduino at each corner of the plate and use the wire library to transfer information to the control hub. Which cable connector to use for such a transmittion of data? And which cable/connector to use for the power(30A,12V)?
Or should I just make a connector at each corner, minimum 12pins(vga connector) and a power connector(which one?) Then run the 4 cables to the control unit or run it to one corner  and there combine it to 11+11+9+9+gnd = 41 pins connector to the control unit and a 120A cable to the power supply.
Attached is a eagle picture of the system layout.
7  Using Arduino / Storage / OpenLog on: September 27, 2012, 09:56:53 am
I have a project where space is essential. I have a Rc transmitter which sends info to a frsky receiver. In the robot i have a one motor with an esc and a potentiometer as feedback for position.

So this means i need:
1 pin for rc signal in(ppm)
1 pin for rc signal out(ppm)
1 pin for potentiometer in(adc)
1 pin for telemetry out(tx)

In addition it would be nice with
GPS in (rx)
Altitude(ADC or spi/i2c)

Can i use it with some clever programing and resoldering?

8  Using Arduino / Programming Questions / Re: XBEE on: May 31, 2012, 07:56:38 am
I just used this code to test that the shields were working, and I sent +++ from the terminal from arduino and got OK back most of the times, sometimes after sending it 2-3 times.. So i should make an external power supply for them?

//Serial Relay - Arduino will patch a
//serial link between the computer and the Bee Shield
//at 9600 bps 8-N-1
//Computer is connected to Hardware UART
//Bee Shield is connected to the Software UART

#include <SoftwareSerial.h>
#define RxD 2
#define TxD 3

SoftwareSerial mySerial(RxD,TxD);

void setup()
    pinMode(RxD, INPUT);
    pinMode(TxD, OUTPUT);
    mySerial.begin(9600);               // the Bee baud rate 
    Serial.begin(9600);                 // the terminal baud rate 

void loop()
       mySerial.print((unsigned char);
    else  if(mySerial.available())
       Serial.print((unsigned char);

9  Using Arduino / Programming Questions / XBEE on: May 31, 2012, 04:38:39 am
I have 2 arduinos(uno and mega) each of them fitted with an xbee shield. I got both them to send me back OK when i send +++ to them, sometimes I need to seed two or three times before i get an answer, any ideas why?

Well what i want to do is to take the value read on analog0 from one of the arduino send it to the other one, the other arduino also reads analog input at A0 and then send both values + timestamp to my laptop over usb. Sth like this Time, A0Local,A0Remote

The problem is that I have problem finding any good tutorials to do this.

I have these XBees:

this shield on the arduino uno 5V:

this shield on the mega 5V:

any tip were to find information on how to do this would be appreciated.

10  Using Arduino / Displays / Re: Scrolling display on: January 14, 2012, 04:39:52 am
but lcd.printIn("") does not clear the second line... what works is lcd.printIn("                                         ")
but that is bad programming style...
11  Using Arduino / Displays / Scrolling display on: January 13, 2012, 08:23:36 pm
I just ordered a lcd shield of this type.. and using this libary

My code does what it is supposed to do(alternating two digital pins depending on button state), however the display does not to do what I want to do. Both lines are cleared when the button is relased and the top line does not scroll, how can I fix this?

Thanks Kim

//example use of LCD4Bit_mod library

#include <LCD4Bit_mod.h>
//create object to control an LCD. 
//number of lines in display=1
LCD4Bit_mod lcd = LCD4Bit_mod(2);

//Key message
char msgs[5][15] = {
  "Right Key OK ",
  "Up Key OK    ",
  "Down Key OK  ",
  "Left Key OK  ",
  "Select Key OK" };
int  adc_key_val[5] ={
  30, 150, 360, 535, 760 };
int NUM_KEYS = 5;
int adc_key_in;
int key=-1;
int oldkey=-1;

int relayPin1 = 26;
int relayPin2 = 28;

void setup() {
  pinMode(relayPin1, OUTPUT);  //we'll use the debug LED to output a heartbeat
  pinMode(relayPin2, OUTPUT);  //we'll use the debug LED to output a heartbeat

  //optionally, now set up our application-specific display settings, overriding whatever the lcd did in lcd.init()
  //lcd.commandWrite(0x0F);//cursor on, display on, blink on.  (nasty!)
  lcd.printIn("Use Up Key for Opening Resin Valve and Down Key for Opening Hardener Valve");


void loop() {

  adc_key_in = analogRead(0);    // read the value from the sensor 
  digitalWrite(13, HIGH); 
  key = get_key(adc_key_in);         // convert into key press

  if (key != oldkey)     // if keypress is detected
    delay(50); // wait for debounce time
    adc_key_in = analogRead(0);    // read the value from the sensor 
    key = get_key(adc_key_in);         // convert into key press
    if (key != oldkey)
      oldkey = key;
      if (key >=0){
        lcd.cursorTo(2, 0);  //line=2, x=0
        if (key == 1){
        if (key == 2){

        lcd.cursorTo(2, 0);  //line=2, x=0



// Convert ADC value to key number
int get_key(unsigned int input)
  int k;

  for (k = 0; k < NUM_KEYS; k++)
    if (input < adc_key_val[k])

      return k;

  if (k >= NUM_KEYS)
    k = -1;     // No valid key pressed

  return k;

12  Using Arduino / Sensors / Re: Mixing epoxy on: June 07, 2011, 04:26:11 am
An epoxy with a ratio of 2:1 would use one pipe "piston" full, with a 2" inside diameter, the other with a 1" inside diameter
well its volume, and A = pi*D^2/4 ...

How do you suggest getting the epoxy in to the syringe? I have 1 barrel with hardener and one with resin. Why always focus on volume mixing rate and not use a scale and just stop at the required amount?

For the mixing part, what about a mix master or a magnetic stirrer or sth like that? How can u get a nozzle to mix it well?

13  Using Arduino / Sensors / Re: Potmeter on: June 06, 2011, 11:56:03 am
Here is a rough sketch of a setup with 3 proximity sensors to read out the two angles.. Any feedback?
14  Using Arduino / Sensors / Re: Potmeter on: June 05, 2011, 08:23:54 pm
Yupp for the azimuth I have 2 proximity sensor and a rotating disc with holes in it. That way I can detect which way it is rotating.. and also increase the accuracy. The problem with
DCDW ("Dirt Cheap Dumb Wireless") for the angle "telemetry": 
Then I need to add lipo charger, and a solar panel or inductive charging circuit.

So I am not sure that's the way to go...
15  Using Arduino / Sensors / Re: Potmeter on: June 05, 2011, 08:04:25 pm
yes I mean potentiometer

The movement of the line?
Yes I am trying to measure the movement of the line in 3D: 2 angles and radius.
I have an encoder on the drum so I know the radius. Then I will be able to calculate the position of the end of the line.

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