attachInterrupt(interrupt, function, mode)

Description

Specifies a function to call when an external interrupt occurs.
Replaces any previous function that was attached to the interrupt.
 Most Arduino boards have two external interrupts: numbers 0
(on digital pin 2) and 1 (on digital pin 3).

Parameters

interrupt: the number of the interrupt (int)

function: the function to call when the interrupt occurs; this function must take no parameters and return nothing. This function is sometimes referred to as an interrupt service routine.

mode defines when the interrupt should be triggered. Four contstants are predefined as valid values:

    LOW to trigger the interrupt whenever the pin is low,
    CHANGE to trigger the interrupt whenever the pin changes value
    RISING to trigger when the pin goes from low to high,
    FALLING for when the pin goes from high to low.


Surely, a FALLING edge on an interrupt, get the time..

But, can you change it (when the IRQ is triggered) to a RISING edge?

if so, grab the time and compare?

After having it for a few days, I deleted the firmware.

You're right, it's slow refresh rate and hangs and has bugs and other issues, so I dumped it for this which is claimed to be 10-100x faster
written by "BenF" whoever Ben might be.

Basically, holding down - while you power on brings up the upgrade firmware, step 2, copy 1 file at a time to temp drive the nano brings up
first the core files then the app, in hex format, it will reboot each time you copy a file..

heaps of improvements on this version and it is considerably faster not the claimed 100x lol  (I attached the firmware)

The PDF on how to use it is in the rar file, the new version is much better, it handles up to about 500khz before it starts to get into trouble...

Arduino  > Files > Examples > Digital > 1. Blink without Delay.

The "metal tip" will contain gnd and the positive signal.

little notches on the pin usually a black line to indicate where 1 ends, i find it surprising this works...

eg  Audio Source > Amplifier > Speaker


So what are you touching? before or after the amplifier stage?

thing is... using an arduino will give you what you need for example, your using a sledge hammer (arduino being the sledge hammer) to crack a nut open with...

eg a 555 timer and few components for less than a dollar will give you the same results...

a pot can be hooked up to the arduino easy enough via a0 5v out > pot > analog in... as you adjust the pot you can increase / decrease the frequency without relying in a computer to feed the data to it..

look up 555 circuits, or even a gate oscillator (fewer components)

failing that go and buy a 1 or 10k pot and feed into to an analog port

rows 7 and 12...  Any of them...  or all Now for a real Trick... cj how much voltage?

What's the forward voltage drop per diode? and the Voltage/current supply is rated what? lol

"can you find the led"


about the 4th image down on this page below


 http://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html


no i can't!!! am i blind?

why not slowly increase/decrease the frequency until you see the desired results on camera with a potentiometer?

So how come there's a fuse to make it read protected? are you sure it can't be overwritten to make it extractable again?.

Solution would be writing to the eeprom with a couple of values and your program simply halts if they are not precise and there at the right
location or pattern, maybe you could shift the bits somehow making it complicated enough to break it without specialized tools...

That however crude is a more secure method it has to be....

the battery 12v does ok as a filter for the alternator, a couple of caps an inductor coil, a linear regulator...

i've had all my circuits run fine from a car without much issue (but they were not sensitive to emi unlike logic ic's) ....

just use the audio jack out and use the usb for power 5v, all you need then is a 5v amplifier

I figure I'm setup now with most all the test equipment I need at home. I started with this scope but as good as it is the display is a bit to small so I bought a DS203 and the screen is a lot more readable. I also found a logic analyser to be very helpful so purchased a ScanaLogic2 and it has been more useful than the scope.

A logic thingy sounds like a good tool to have

I don't know any "expert" who would diss gaining a whole new perspective on their hobby, certainly not at the incredibly low cost this sort of device is available at.

https://www.youtube.com/watch?v=Xh9FNRpta9s

EEVblog #86 - Buy a real Analog Oscilloscope PLEASE!

I was going from his opinon and i'd consider him an "expert" but for my needs i don't see how what he says hold's true.

while i read the rest of your and the others posts.....

1. I know it's not as good as the real deal.
2. it's hell of a lot cheaper than the real deal.
3. for my needs, all of my circuits are fine, I don't need to read anything beyond a few hundred khz.
4. i've never has an oscilloscope and to get my feet wet, $65 was worth it.

Knowing all that

https://www.youtube.com/watch?v=hLSzo9F4qbo&feature=youtube_gdata_player

That's connected up to an Arduino with the example code.

Code:

/*
 Fade
 
 This example shows how to fade an LED on pin 9
 using the analogWrite() function.
 
 This example code is in the public domain.
 */

int led = 9;           // the pin that the LED is attached to
int brightness = 0;    // how bright the LED is
int fadeAmount = 5;    // how many points to fade the LED by

// the setup routine runs once when you press reset:
void setup()  {
  // declare pin 9 to be an output:
  pinMode(led, OUTPUT);
}

// the loop routine runs over and over again forever:
void loop()  {
  // set the brightness of pin 9:
  analogWrite(led, brightness);   

  // change the brightness for next time through the loop:
  brightness = brightness + fadeAmount;

  // reverse the direction of the fading at the ends of the fade:
  if (brightness == 0 || brightness == 255) {
    fadeAmount = -fadeAmount ;
  }     
  // wait for 30 milliseconds to see the dimming effect   
  delay(30);                           
}

First of all, it might be "tacky" but I just learnt how PWM works, i connected it up to TR/RV lines and watched the data being sent, i've only had it a day and
i've learnt so much!  that alone is value to me, i've learnt and will continue to learn new things with this tool, i'm not interested in reading scientific measurements.

I'm having so much fun with one, I want to get my hands on a full sized 2 channel scope, but i'd probably not even contemplated doing such a thing if not
for the fact i took a risk free try with one of these ARM FPGA devices for $65!

I'm not starting a flame war, I just don't see why the "experts" are so harsh on these devices, would you deny yourself a multimeter because it can only measure voltage?
even if all you need is to measure voltage?

i'm refering to the yellow wires at the bottom, it's oddly shaped cap!