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16  Using Arduino / Project Guidance / Re: Cheap way to connect an Arduino to a Android Smartphone via bluetooth on: February 04, 2013, 09:59:08 am
Thanks for the input guys

I'll get myself one of those devices and play with it.

17  Using Arduino / Project Guidance / Re: Cheap way to connect an Arduino to a Android Smartphone via bluetooth on: February 04, 2013, 05:22:44 am
Hi teckel,

do you have any code examples of how to get this working with arduino and android?

18  Topics / Home Automation and Networked Objects / Re: Android application for control your arduino board on: February 04, 2013, 05:12:59 am
Please help some newbies to Android here and post some code snippets or tutorials.

Did you use the USB host shield or Andorid ADK mega or google adk?

Many Thanks
19  Topics / Device Hacking / Re: Android and Arduino development on: February 04, 2013, 05:08:20 am

thanks for the book recommendation and links. I'll share anything I find that may be of use.

I'm following this tutorial today (Monday 4th Feb): This one is about sending data to the Arduino but there are ones to do it the other way around.

The people at circuits@home seem helpful with lots of useful post on their site, and they may also answer some posts on the blog.

Have you tried running any code yet?

20  Topics / Device Hacking / Android and Arduino development on: February 02, 2013, 06:26:47 am

I'm new to Android (some Java SE and xml, eclipse / netbeans experience), but I have been playing with Arduino (mostly Uno) for 18 months now. Is this the right place on the forum that I should post questions. I am using the Uno with a USB host shield (cicuits@home).

I think I don't have to buy an arduino (eg Arduino ADK Rev 3 Board) or google dev kit (very expensive and too complicated)  because I have most of the parts in my uno and USB shield. But I am not sure. My guess is that those new dev kits evolved from the work done by those guys who contribute to circuits@home (Oleg maybe?)

So this is my first question. Are the libraries and code examples for the Arduino ADK compatible with my (uno & shield) setup?

Many Thanks
21  Topics / Device Hacking / Re: Create a spark or burning coil with Arduino on: January 28, 2013, 03:02:12 pm
I don't think there are any relays on the standard arduino motor shield, it uses H-bridges on a chip.

You can use an arduino pin to get a transistor to trigger a relay. The relay can then switch 9v (say 2 Amps) this can make thin nichrome wire glow hot. Wrap the nichrome wire around a match (non safety type) and you have a homemade igniter. You could use a mosfet instead of a relay.

22  Topics / Device Hacking / Re: Create a spark or burning coil with Arduino on: January 28, 2013, 10:33:24 am
Have a look at this I made for remotely firing fireworks. I used an arduino to control a relay and nichrome wire.

All the information needed including videos and circuits is on the blog.
23  Community / Bar Sport / Re: People hate resistors for their LEDs on: January 17, 2013, 10:51:28 am
When doing a quick test, I like to plug one leg of a standard led into the Arduino female. I have some 560 Ohm resistors soldered onto flex jumper wires at one end, and  croc-clips on the other. This is so I can clip the croc onto the other LED leg, and plug the loose end of the resistor into another female. The croc-wire-resistor makes it easier to move between components and arduino pins.

Come to think of it a croc-resistor-croc might also be useful.

24  Community / Exhibition / Gallery / Re: Relaxino on: January 17, 2013, 10:36:58 am
I was at Uni in the 80's. Pre-web-istory and the fax-age !

They did put a sensor on my finger. I think, as you say, you can sense O2 and heat rate on the finger. I saw an article for the CES show in Las Vegas had medical sensors for mobile phones and some of these used the type of sensor you mention. Skin resistance sounds good.

I'll look at other sensors too for measuring stress / relaxation. Blood pressure comes to mind, but the devices used on me were really annoying, and involve arm-squeezing devices, motors etc...

I wonder if you can sense the pulse in the carotid artery made by the heart beating, and somehow calculate the energy in the wave, and correlate that with instantaneous blood pressure?  There seems to be quite a tangible displacement in that pulse.

I don't want to go the whole hog and make a lie-detector type device, but there must be something in between.

25  Community / Bar Sport / Re: People hate resistors for their LEDs on: January 17, 2013, 09:41:37 am
Hi Guys,

hope this isn't a proverbial grandma-egg-sucking  moment, but you can get leds suitable for 5v use with built in resistors

I think there are 12v ones too.

I don't like fritzing either, I prefer circuit diagrams every time.
26  Community / Exhibition / Gallery / Re: Relaxino on: January 17, 2013, 09:16:23 am
Hi Geoff,

Cheers, I'll take that on. I worried about that delay issue with interrupts, I should bite the bullet and improve the code.

Many Thanks

27  Community / Exhibition / Gallery / Re: Wall-E's Friend on: January 17, 2013, 08:26:39 am

That's inspirational and cute. I would like to have a go myself, so I'm looking forward to seeing more installments and especially code - do you have a Blog page?

28  Community / Exhibition / Gallery / Re: Relaxino on: January 17, 2013, 08:07:54 am
Thanks for the +ve feedback Geoff,

I agree with you 100%. I had a heart attack last summer so these things are uppermost in my mind. I use the breathing relaxation technique all the time, but now I have biofeedback too.

I wanted something that gave feedback which  correlated better with what you are feeling. As I said you can see the leds sync with you feeling the pulse on your neck. The 30 beat average is just to get a value to compare with the target.

I guess this could also be used for athletic training ie set high value targets and get simple visual biofeedback. I haven't tried it for that yet, but I think the chest-strap version of the pulse monitor would be more suitable, to cope with the constant jogging around So setting upper and lower targets could be useful for training and cool-down.

You need to exercise when recovering from heart problems but within limits. It could help with that too because you can see when it changes over.

Did you see any problems with the code at all? My background is in Biology so I lack some confidence in the coding field.

Best Regards

29  Community / Exhibition / Gallery / Relaxino on: January 16, 2013, 12:23:57 pm

I made a first attempt at a simple relaxation device. I used the Seeed Studio ear-clip heart rate monitor available in th UK from

Explanation of how it works.
It works by measuring you heart rate over 30 seconds and taking an average. Each heart beat is displayed on either a red or green LED. An LED flashes at the approx frequency of your heart rate to give you biofeedback. You set a target rate in the code, so a red LED flashes when you are above target and a green one when you are at, or below the target heart rate. This allows you to try to relax and get feedback on how you are doing. Target is assessed by averaging over 30 beats.

Set the target initially close to your resting heart rate (mine is typically 65). It needs 30 beats to get going so both LED's will flash on startup / Arduino reset. The word "BEAT" will print in the monitor for each heart beat detected, and an LED will flash on each heart beat. You can check by feeling the pulse in your neck and watching the LED - both should be approx. in sync.

Lie or sit down and try to relax, taking long deep breaths in and out, empty your mind and gently focus on the LED light (being in the dark helps so you can see the pulses through closed eyelids).

Gradually increase the length of the breaths, counting if you need to: 6-8 seconds for in, 6-8 seconds for out (or do whatever you can manage). Build up to longer and longer ins and outs. Don't rush it and get out of breath - your heart will beat faster!

With practice it can help you relax by providing the simplest of biofeedback

Constructive comments very welcome.

/*  Program to measure and display heart beats on two led's (and on serial monitor for debug)
*   Green led flashes at approx freq of your heart rate when you are at or below your target,
*   if you go above this (eg 65 bpm) the red.
*   led flashes at the approx freq of your heart rate
*   You can check by feeling your pulse
*   in your neck and looking at LED - both should be in sync
*   C. Turner 16/01/2013.

*  Seeed product wiki
*  Avaialible in UK here:
*  More detailed project write-up here:

// Sketch is provided "As is" with no guarantees, or support from the Author.
// Help with Arduino and shields can be found by joining the forum on the Arduino website:

unsigned char HIpin = 13;//red led = over target & use 560 Ohm resitor in series
unsigned char LOpin = 12;// green = @target heart rate or below & use 560 Ohm resitor in series
// times
unsigned long t1 = 0;
unsigned long t2 = 0;

unsigned long counter = 0; // count interrupts = beats
unsigned long secsElapsed = 0; // time for 60 beats
unsigned long myCount = 0; // heart beat count so far

float heartRate = 0; // instantaneous rate
float averageHeartRate = 0;// ave over 30 beats

boolean beatDetect = false;

void setup()
  pinMode(HIpin, OUTPUT);
  pinMode(LOpin, OUTPUT);

  Serial.println("Please ready your ear clip.");
  digitalWrite(HIpin, HIGH);// red led off

  delay(2000);//time to place clip, note that some people's earlobes are too thick (mine are)
 // I had to place it on the main ear. May need to play until you get sensible results.
 // change to 5000 or more if need more time.
  digitalWrite(HIpin, LOW);// leds off
  digitalWrite(LOpin, LOW);
  Serial.println("Heart rate test begin.");// debug

  t1 = millis(); // set start time.

  attachInterrupt(0, interrupt, RISING);//set interrupt 0, digital pin 2 -
  //Seed / grove heart monitor out pin is attched here.
void loop()

  if (beatDetect == true)// if interrupted on pin 2 ie beat was detected

    Serial.println("BEAT");// debug: print BEAT on each interrupt

    if (counter > 20 )// use heart rate when 20 beats averaged
      Serial.println("Heart Rate is: ");// debug
      averageHeartRate = heartRate;
      Serial.print(averageHeartRate);// debug
      Serial.println();// debug

    counter = counter + 1 ;

    t2 = millis(); // check time

    myCount = counter;// heart beats so far
    secsElapsed = (t2 - t1 ) / 1000 ; // seconds elapsed
    heartRate =  (float(myCount) / float(secsElapsed) ) * 60;// beats per minute
    beatDetect = false;// reset for next interrupt (beat)

    if (counter == 61)
      counter = 0; // reset counter after 30 beats
      t1 = millis(); // reset t1 to millis()

    //display the info **************************
    if (averageHeartRate != 0)
// SET TARGET HEART BEAT HERE ++++++++++++++++++++++++++++++++++++++++++++++++
      if (averageHeartRate > 63)// my average resting heart rate = 65 bpm - choose your own
        //HIGH target RED led
        digitalWrite(HIpin, HIGH);// red led on
        delay10thsOfSeconds (1);// flash at heart beat rate
        digitalWrite(HIpin, LOW);// red led off
        delay10thsOfSeconds (1);// flash at heart beat rate
        digitalWrite(LOpin, LOW);// green led off

      if (averageHeartRate <= 63) // my average resting heart rate = 65bpm choose your own
        //LOW target green led  
        digitalWrite(LOpin, HIGH);// green led on
        delay10thsOfSeconds (1);// flash at heart beat rate
        digitalWrite(LOpin, LOW);// gree led off
        delay10thsOfSeconds (1);// flash at heart beat rate
        digitalWrite(HIpin, LOW);// red led off

    else if (averageHeartRate == 0)// when starting up flash both leds

      digitalWrite(HIpin, HIGH);// red led on
      delay10thsOfSeconds (1);// flash at heart beat rate
      digitalWrite(HIpin, LOW);// red led off
      delay10thsOfSeconds (1);// flash at heart beat rate
      digitalWrite(LOpin, LOW);// green led off

      digitalWrite(LOpin, HIGH);// green led on
      delay10thsOfSeconds (1);// flash at heart beat rate
      digitalWrite(LOpin, LOW);// gree led off
      delay10thsOfSeconds (1);// flash at heart beat rate
      digitalWrite(HIpin, LOW);// red led off


  }// end of beat detected


void interrupt()
  beatDetect = true;


void delay10thsOfSeconds (int multi){// delay multi x 0.1 sec

  for (int i = 1; i < (multi * 10); i++) // wait 10 = 0.1 sec
    delayMicroseconds(10000);   // multi x 100 x 10000 us


Attach the anodes of a green LED on digital pin 13, and a red LED on pin 12.
Current limiting resistors used for the LED's are 560 Ohm and connect cathodes via the resistor to ground pins
The device uses a RISING interrupt on pin 2,  so I attached the output wire (yellow) of the heart monitor to pin 2 of the Arduino. Black wire goes to ground and red to +5v.
Attach the ear clip to you left ear. Beware some peoples ear lobes are too thick (mine are) so play around with the position. I had to put it on a thin flattish part of my ear.
Upload the code to the board.
Open the serial monitor

30  Community / Exhibition / Gallery / Re: Female version Seeeduino on: December 29, 2012, 10:20:47 am
I was thinking about this cool design over the Christmas holiday and thought it would be great to see a new expansion of arduino board design into fun shaped boards with nice colours and patterns etc... as long as you can still fit shields on them. (I think it was due to seeing lots of new toys - I'm still a big kid really).

I like circular and round objects and symmetry. I know there is the lily pad but that is a completely different implementation.

Round boards with Ying / Yang symbols, Celtic Knots, dragons etc... would attract me. I like ancient cultural mysticism and practice martial arts. Especially nice if  leds are strategically placed in the designs. smiley-cool

There is also an industry based on personalised printing onto everyday objects - why not Arduino products too? I'm not really suggesting putting your face on an Arduino, but hey, whatever turns you on smiley-grin.

As engineers and scientist we might scoff. However, invention and imagination can create magic, and science / engineering is the real magic in our lives. It is easier to engage youngsters when ideas are presented with a bit of magic.

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