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1  Using Arduino / General Electronics / Re: Choosing the power supply on: January 11, 2014, 02:48:22 am
@ SeanJD

Can I offer 2 ideas ?

In 2011, I did a project using  Opto-couplers.  The Arduino board has it own power supply, and the other end - USB computer side has it own as well.  I was able to communicate with the Arduino and Computer using Processing. Do a search of the forum. 

Also you can do the same using RS232. USB to RS232 attach at the Tablet end, And a MAX232 at the Ardiuno end. That will take care of the communication part.

The power part with the 12 V, that have to provide to the Ardiuno and sensors.

Just 2 ideas.

I have 2 Android device. 1 tablet and a cell phones. Theses two devices don't have enough currents to power Arduino with sensors.  A lonely board... yes, but not a fully loaded board with sensors .... motors !!! no way !!! I don't want to damage my cell phone and my tablet.

@ CrossRoards

Nice to "see" you. Wrote a book ! Nice. 
2  Using Arduino / Project Guidance / Re: An LED bar graph tachometer on: May 14, 2012, 01:06:08 pm
That is a cool project.

If I where you, I will split the project in two parts.

Part One : Code testing using a 555 , wired it into a variable frequency generator or use a frequency generator.

Convert RPM --> Frequency

For display, I will use a 2 X 74HC595 or 1 X MAX7219 or use the digital pins ( you are a bit limited ) .

Bear in mind, the coding and wirring for display will be different for each methode use.

Get that working first.

Here a pseudo code :

Code:

RPM sample  Frequency  -- > RPM

Calculate a value to be display RPM --> numbers of leds  OR

Frequency --- > numbers of leds to display

Figure first : 1 segment - led  = what is the value in RPM / Frequency

Example : 100 RPM = one segment on  - data = 00000001
               200 RPM = 2 segment on   - data = 00000011
               300 RPM = 3 segemnt on  - data = 00000111
               400 RPM = 4 segment on - data = 00001111
               the rest...

Display the leds.



Part two :

The circuit to sample the RPM and connect with the code and display circuit. 

Anyway, that is my 2 cent idea
3  Using Arduino / General Electronics / Re: Standalone Arduino Serial Communication on: May 03, 2012, 01:07:14 pm
The breadboard look fine. But I did not see the positive +5 V connect with the other +5 V rail. Same goes to the gnd rail. I hope you did that. And you forget a reset button. The resistor at reset pin is OK.

For a standalone project, it look OK, beside the two rail ( + 5 and GND )  not being connected... maybe you did ? 
After that, you connect the FDTI board ( RX, TX, DTR ---> 0.1 uF ---> reset ) to load up your code, and to power up the AT chip , oh yeah, disconnected the +5 V from the regulator if you use the FDTI board.

You check you code by using the serial monitor .... That is the FDTI board job, if you got a message, than your code is working.

THAN you connect the +5 V regulator, disconnected the FDTI board, re-connect your X-Bee board. Power up the AT chip.

If that did not work ( It look that way ) , well the X-Bee is : Not transmitting or  The receiver is not receiving... my guess
4  Using Arduino / Project Guidance / Re: Controlling an analog automotive tachometer on: May 02, 2012, 01:02:38 pm
Thank for the tips, justjed, I have to look into the Ford Focus Can Bus to have the tach signal.  Hum... by just thinking about it, when my car was being tested for emissions require by the Ministry of Transportation - Ontario, the tech only connect the CAN bus to a computer system and can read all the info when the car run on a tread mill.

Yes, it is possible... I will do a search about it. I will look at the book "Haynes Repair Manual" Ford Focus 2000 to 2005.

BTW, justjed, my car is fix, $3000 for a 60 000 km motor. ( include installation ).  smiley-eek Just to let you know. The motor fail around 150 000 km.   smiley-eek-blue

My car is fine now, BTW
   
5  Using Arduino / Project Guidance / Re: Powering Foot Tall 7 Segment Display on: May 01, 2012, 12:27:54 pm
That big display look cool to display your house number. $50 for each digit, I need two...hum.. I better build my own.

Still look cool that display, BTW  Hum... a giant clock display ?  or count down display ? Still cool.

Producing 35 V for it...  smiley-roll that may be a "tiny" problem.  smiley-confuse

My opinion.
6  Using Arduino / Project Guidance / Re: Controlling an analog automotive tachometer on: May 01, 2012, 12:16:39 pm
I am glad you got it working. I am just curious, did you have a datasheet ? Others maybe interested doing the same thing.  Even me, I may add a tach for my car.
7  Using Arduino / Project Guidance / Re: Controlling an analog automotive tachometer on: April 30, 2012, 06:59:48 pm
Quote
Analog rev counters are usually frequency meters driven by the 12V square wave off the coil -

Hum... I did know about that type.

In that case... TTL signal ----> 12 V signal    a simple transistor circuit can do just that. 

Need : TTL from Arduino --> NOT inverter <-- 74LS04 or 74LS14  ----> base resistor of 4.7 K ---> a 2N3904.  For Rc = 1 K , take signal from the collector <-- Your 12 V signal.  Connect Rc = 1K to collector and the another end, a 12 V source, and of course, the emitter to GND and all GND together.
8  Using Arduino / General Electronics / Re: cant communitcate with the arduino on: April 30, 2012, 06:42:33 pm
Quote
hi Techone, my setup is the same as you explain expect for the crystal, pins 9, 10 with the 22nf c's, the circuit diagram definatly says pins 9,10

I am not worry about the 22 pF cap by not being there. My breadboard version don't have them anyway. So you did have a 0.1 uF in serie --> between   the DTR and the RESET ? Yes ? With that cap there, no need to press the reset button during an upload of a new program. And what type of FDTI board you are using ? Because some type are : RX --- > RX   and some are RX --- > TX.

But uploading a bootloader to a blank ATMEGA328, that one... can not help at this time.
9  Using Arduino / Project Guidance / Re: Controlling an analog automotive tachometer on: April 30, 2012, 06:27:28 pm
It is possible. First, you need a datasheet for the Analog Automotive Tachometer.  I am assuming it is a simple ammeter. <-- I may spell this one wrong... It is a needle meter. It work the same principle of a needle multimeter. The automotive store has those.  I do have some needle meters here, and the only info for them is : At max current <-- needle at max value, what is the current ? The type I have are 10 mA ?  type ? hum.. I need to check it out. Anyway, it work like : 0 current = no needle mouvement. at a certain current example : 10 mA - full needle mouvement, more than the current rated, it may damage the needle / internal coil.

If you have a datasheet for this particular meter, you may have more insight.

 
Quote
I was figuring I could just feed a signal into it but I am not sure what type of signal I would need to use?

Not that simple... The Arduino is Digital... 0 V = 0 and 5 V = 1  in and out, can take an analog signal 0 V to 5 V in, and a PWM signal , a digital signal , with a duty cycle. Therefore you need to "convert" a digital signal into a current signal.

Ok here the "trick" --->   Digitals ---> analog <-- Voltage  ----> current.  You got to use an external circuit. An Digital to Analog converter and  a voltage to current converter. You have to use a few Op-Amps. <-- Operational Amplifier.

To use the PWM, you need : PWM --> Intergrator - > Buffer op-amp --> Voltage to current converter.

I hope that give you some insights. those are "Block" diagrams, you simply design each block to make this project to work.

I am sorry that it is not a simple answer.

  
10  Using Arduino / General Electronics / Re: Can you get a negative and positive voltage out of the same source? on: April 30, 2012, 01:00:17 pm
What about the MAX680 ?  That might work, has long the application load is "very" light. 

The datasheet :  http://www.hvwtech.com/products_view.asp?ProductID=1107

To buy it : http://www.futurlec.com/Maxim/MAX680.shtml

11  Using Arduino / General Electronics / Re: cant communitcate with the arduino on: April 30, 2012, 12:30:46 pm
To upload a program into an ATMEGA328 Chip with Arduino bootloader already in, You need :

1. a USB -TTL board.
2. Connect them right. What is your USB -TTL Adapter ?

Let take the one here : http://www.hvwtech.com/products_view.asp?ProductID=1107 A FTDI breakout USB-TTL adapter.

But first, make sure the Arduino chip is connect right.

1. The Vcc : pin 7 and pin 20. -- + 5 V
2. The GND : pin 8 and pin 22  -- gnd
3. The X-Tal : pin 23 and pin 24 -- 16 MHz Crystal and 2 X  22 pF cap to GND.

To connect the FTDI :   For that particular board :  RX --- > TX pin 3   TX --- > RX pin 2

And.... Connect the :  DTR ---- > 0.1 uF cap -----> Reset pin 1   The cap is in serie.

In the IDE, choose the right USB port number and the right board. The board I choose is : Arduino Pro ( 5 V 16 MHz ) ATMEGA328.

Try it and see what happen...

If you have still problem, a picture of your setup will be nice. 
 
       
12  Topics / Robotics / Re: Help Programming Quadruped on: April 29, 2012, 10:53:56 pm
Quote
That ant bot is pretty neat, have you seen the videos, very smooth and realistic movement.

Not Yet. It will be cool.
13  Topics / Robotics / Re: Help Programming Quadruped on: April 28, 2012, 07:25:33 pm
Thanks Graynomad for the links. I will check it out.

BTW check this cool & mean "bug" http://www.lynxmotion.com/p-855-a-pod-combo-kit-for-bot-boardssc-32bap28-and-ps2-controller.aspx... the price is : $1337.00 ...  smiley-eek-blue  Man ! expensive !

Quote
Also check out these forums

http://www.lynxmotion.net/
http://www.societyofrobots.com/robotforum/

There are guys there more into robots then the average member here.


Cool forums. Thanks for the link.

14  Using Arduino / Programming Questions / Re: How to monitor a switch's state and do X if switch has remained in state B on: April 28, 2012, 06:38:12 pm
I don't know this code may give you some idea about the state of a switch and help you for some insight...

Here a code. The code is a gear shifter. It got a Up and Down button. The switch go from HIGH to LOW. I hope it give you some insight.

Code:
/*
  size : 1774 byte
 
  Version 2.1
 
  file name : gearshifter.pde
 
  It simulate a gear shifter using 2 push-button switch.
  The circuit use a 7 segment display and 2 led for the
  simulated selenoid.
 
  Gear sequence:   Gear Number   A   B
                       1         1   1
                       2         0   1
                       3         0   0
                       4         1   0
 
  Here the parts you need :

  1 Commun Anode 7 segment Display
  2 Red LED
  2 Push Button Switch
  9 2N3904 NPN Transistor
  11 1 K resistor
  9 330 ohms resistor
 
  How it work :
 
  1. Init the gear at 1.
  2. Press Upshift Button to increase the gears
  3. Press Downshift Button to decrease the gears.
 
  Program by Serge J Desjardins aka techone / tech37

  Compile and Tested <-- Test on a breadboard

  Disclaimer:

  I am not responsible for any damages, losses, injuries or death.
  The user is responsabe for any damages, losses, injuries or death.
 
  And Murphy's Law is always there, bear that in mind.
   
*/
// Arduino Digital pins
const byte outpin[9] = {4,5,6,7,8,9,10,11,12};
const byte inpin[2] = {2,3};
// Selenoid and Display array pattern
boolean gearone[9] = {1,1,0,0,0,0,1,1,0};
boolean geartwo[9] = {0,1,1,0,1,1,0,1,1};
boolean gearthree[9] = {0,0,1,0,0,1,1,1,1};
boolean gearfour[9] = {1,0,1,1,0,0,1,1,0};

byte gear;

int upshift=1;
int downshift=1;
int oldupshift=1;
int olddownshift=1;

boolean state=0;

void setup()
{
  // init the digital pins
  for (int i=0; i<9; i++)
  {
  pinMode(outpin[i],OUTPUT);
  }
  pinMode(inpin[0],INPUT);
  pinMode(inpin[1],INPUT);
  // Put in gear one
  gear=1;
 
  for (int i=0;i<9;i++)
  {
    digitalWrite(outpin[i],gearone[i]);
  }
}

void loop()
{
  readswitch();
  while(state==0)
  {
    readswitch();     
  }
  // a switch as been pressed
  // Check for the upshift
  if ((upshift==0) && (state==1))
  { 
     gear++;
     if ((gear>=1) && (gear<=4))
     {
       switch(gear)
       {
         case 1: selectone();break;
         case 2: selecttwo();break;
         case 3: selectthree();break;
         case 4: selectfour();break;
       }
     }
     else gear=4;
   }
  // check for the downshift 
  if ((downshift==0) && (state==1))
  { 
     gear--;
     if ((gear>=1) && (gear<=4))
     {
       switch(gear)
       {
         case 1: selectone();break;
         case 2: selecttwo();break;
         case 3: selectthree();break;
         case 4: selectfour();break;
       }
     }
     else gear=1;
   }   
   
}

void selectone()
{
   for (int i=0;i<9;i++)
   {
     digitalWrite(outpin[i],gearone[i]);
   }
   state=0; 
}

void selecttwo()
{
   for (int i=0;i<9;i++)
   {
     digitalWrite(outpin[i],geartwo[i]);
   }
   state=0; 
}

void selectthree()
{
   for (int i=0;i<9;i++)
   {
     digitalWrite(outpin[i],gearthree[i]);
   }
   state=0; 
}

void selectfour()
{
   for (int i=0;i<9;i++)
   {
     digitalWrite(outpin[i],gearfour[i]);
   }
   state=0; 
}

/* The subroutine is a modify switch example in page
   51 of the book "Getting Started with Arduino"
   
   The switch is configure with a pull-up resistor,
   so it always a 1, when press, it is a 0.
*/   
void readswitch()
{
  upshift=digitalRead(inpin[0]);
  // check upshift transition
  if ((upshift==0) && (oldupshift==1))
  {
    state=1;
    delay(50);
  } 
  oldupshift=upshift;
  downshift=digitalRead(inpin[1]);
  // check downshift transition
  if ((downshift==0) && (olddownshift==1))
  {
    state=1;
    delay(50);
  } 
  olddownshift=downshift; 
}
15  Using Arduino / Programming Questions / Re: converting char to int on: April 28, 2012, 06:34:09 pm
I did something like that using an Arduino to read a pot value, send it to a PC and the PC send back the voltage value.

I did a code for the Ardiuno and for the PC, a Processing code. I was doing a test using an DYI opto-coupler linker.

Here the tread : http://arduino.cc/forum/index.php/topic,94382.0.html  Just look at the latest code in the tread. I know, it got a bug in it, but the value being send by the Arduino, and the value being send by the PC is OK. The convertion program section of both code ( Arduino & Processing ) is just fine.  About the bug... I have to monitor the serial data going into the Arduino so I can investigated , maybe re-code the receiving section to get it right. The data convertion is just fine. Check it out.
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