Show Posts
Pages: [1] 2 3 ... 39
1  Using Arduino / General Electronics / Re: Detecting battery voltage using bandgap / internal 1.1V reference on: April 08, 2014, 01:39:05 pm

a quick answer to question 2 :

U means  "unsigned"
2  Using Arduino / General Electronics / Re: nrf2410l on: January 26, 2014, 04:41:53 am
You asked for help, Fungus sent you a link which answers your questions (you'll have to download some documents there).
But if you don't know what are MOSI, MISO etc... you need to read and learn what SPI (Serial Peripheral Interface) is and how it works .

edit : BTW, most people here don't answer to private messages : Questions and answers are useful for everyone  smiley-wink
3  Using Arduino / General Electronics / Re: cheaper MOSFET than IRF630 for high-voltage NiCd reconditioning? on: January 06, 2014, 02:57:07 pm
This all sounds like an explosion hazard to me - if you don't want metal shrapnel embedded
in your body don't attempt this.
As I said I've already tried zapping individual cells with ~18V with nothing worse than a small burn on my finger from the spark that formed pressing the wire to the battery terminal.
There is a real hazard of getting hit by a falling meteor if I go outside, but that doesn't stop me from getting fresh air...

as MarkT already told you, 120V is not 18V , and you should be aware than touching the 120V will not only burn your finger, 120V is more than enough to kill you very quickly . It is not a theory, it is just truth.
4  Using Arduino / Programming Questions / Re: Help compiling program on: December 11, 2013, 11:51:58 am
Maybe you should go step by step and begin with the Step 5 of the tutorial :
Step 5: Using the shield in standalone mode
Sending and receiving SMS

Does it work ?
if no, how is the status Led ? is it OFF ? does she blink 64ms ON/800ms OFF or 64ms ON/3000ms OFF ?

I don't know this particular module, but I have a sim908 shield, and mine :
- needs more than 3 seconds to start up
- doesn't answer "OK" to the 1rst 'AT' command -

instead of printing the answer value (0 or 1) , you should print the module response, it would be more useful to see what the module sends.
5  Using Arduino / Programming Questions / Re: Help compiling program on: December 11, 2013, 09:48:41 am

1 - are you sure your module communicates at that speed ??  I doubt it

2- a) which module is it ?
     b) how and where do you tell it it must be in GPS or in GSM mode ?

3- how is it wired ?
6  Using Arduino / General Electronics / Re: Electrostatics on: December 10, 2013, 07:24:00 pm
maybe a project like this one :


edit : I put a picture of "back to the future" , but it doesn't appear  smiley-confuse
7  Using Arduino / General Electronics / Re: arduino and transistor on: December 10, 2013, 05:17:47 pm
the pins of interface logic just  connecte it without programming in arduino.

please, could you explain what it means ?
8  Using Arduino / General Electronics / Re: arduino and transistor on: December 10, 2013, 09:58:38 am
ok i saw it but there no MOSI, sck, ss pins in the arduino
9  Using Arduino / Project Guidance / Re: Digital Inputs/Outputs through serial on: December 10, 2013, 04:05:19 am
Actually, it works, and you can check it, with Serial.print() statements as shown below .
Also, as PeterH says, using 'case' in this situation makes your code more readable.

Once the sketch is uploaded, open the serial monitor and enter 'A' and 'return'  etc....

void setup(){

void loop()
  int val;
  if (Serial.available())
  //  delay(10);
    while (Serial.available() >0)
          switch (val)
               case 'A' :  Serial.println("You entered A");   
               case 'B' :  Serial.println("You entered B");

once you have confirmed it answers what you want, just replace the Serial.println() statements with
digitalWrite() ones  smiley

10  Using Arduino / Project Guidance / Re: I need an if statement to execute only once? on: December 09, 2013, 05:14:30 pm
writing a progam which does what you describe is easy, but let's think about it :

1 - at start, the button is "released" -> nothing happens, right ?
2 - you push the button -> clockwise move, just once  .... still right ?
3 - now you release the button.... nothing must happen ?
4 - you want a anticlockwise movement, OK, so you need to release the button, and, before you release it, you must push it... :
          a - you don't want any movement ? -> OK, but that means that you'll never be able to get 2 clockwise movements without an anticlockwise between. Is tha what you want ?
          b - you want to be able to move several times clockwise (or anti-clockwise) -> OK, but when do you know the anticlockwise movement must happen ?

remember your button has only 2 states, and one of them (release) is true when you don't push it .

I think you need to describe more precisely what you want smiley-wink
11  Using Arduino / General Electronics / Re: arduino and transistor on: December 09, 2013, 12:37:01 pm
thank you, but the datasheet of the dac that i have is in this joint

then what is exactly your question ?
if it is "can I connect digital erduino outputs to digital inputs of the DAC ? " my answer would be "yes, you can"

and the datasheet shows several typical applications circuits that should help you to do what you want to do ( you've not told us about it)
12  Using Arduino / Programming Questions / Re: Problem with extern specifier on: December 08, 2013, 01:16:46 pm
it is not defined within a function, but it is explicitely defined as static :

static     time_t     syncInterval = 300; //  time sync will be attempted after this many seconds

wich makes it only accessible from time.cpp ( am I wrong ?  smiley-roll  )
13  Using Arduino / Programming Questions / Re: Problem with extern specifier on: December 08, 2013, 12:26:00 pm
Hi Jack,

you just need to download and install the Time library in the "libraries" folder, restard IDE and it compiles without error

edit : oups, sorry, remove the 'extern' too smiley-wink

edit2 : and I think you can't use the 'extern' keyword, because, in time.cpp, syncInterval is defined as static, thus AFAIK, cannot be used in another file.
14  Using Arduino / General Electronics / Re: GPRS Shield Blew up on: December 08, 2013, 10:55:35 am
glad to hear nothing else has suffered...for now   smiley-mr-green
We have a capacitors expert here ine the forum, who could tell exactly the actual advantages/inconvenients of using one technology or the other. The visual difference is obviously the size  smiley-lol  , but if you've replaced it with a one of the same value, and if it is rated 16V or more , it will work .
Maybe you should have a closer look to find out why the 2nd GND doesn't work anymore, and maybe fix it
15  Using Arduino / General Electronics / Re: fet vs bipolar transistors... on: December 08, 2013, 08:12:23 am
actually, I would add one or even two 1N4148, because Red Led voltage is often lower than green ones.
If the forward voltage of the red led is, say 2.0V , and if it is 2,8V for the green Led (which is common), then we'll need more 1N4148 if we don't want the red led to be on while the fuse is OK
But, below about 1,8V, no current flows through the Led.  (look at the datasheet, for example : smiley-wink )

Edit : OK, the Led in the link above is a special one - I should have pointed more basic led datasheet, like this one Anyway, the forward voltage is still between 1,8 and 2,2 . If the green one has the same, no problem, but....
Pages: [1] 2 3 ... 39