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1  Using Arduino / Programming Questions / Re: do while in an interrupt on: Today at 04:07:03 pm
micros does not increment when an ISR is being run.

And 500 micros is 100x to long a delay to use in an ISR.

Mark
2  Using Arduino / Project Guidance / Re: Making the needle move on a rev meter on: Today at 02:26:10 pm
We do NOT change the freq when using PWM to control something. We can if we wish select (almost) any freq we like.

Mark
3  Using Arduino / Programming Questions / Re: 'Beginning C for Arduino by Jack Purdum' book errors? Modified Blink program on: Today at 02:15:57 pm
Making count a long is an error. It only needs to be 1 byte long.

Mark
4  Using Arduino / Programming Questions / Re: for loop like basic? on: Today at 11:00:34 am
The a good design tip for micro controller programming is DON'T use for or while loops!.  As for how to use a fro loop just look in the reference section.

Mark
5  Using Arduino / Project Guidance / Re: Making the needle move on a rev meter on: Today at 09:15:41 am
I was correcting  steinie44.

The real question is what are you really trying to do with that meter?

If you just what to make to move then you connect up the coil of the meter as if it where a motor using a transistor and a diode.  You then run the fade example. Look in the playground.

If you have and old fashioned analogue multi meter (AVO meter) just load the fade example and measure the voltage between pin13 and ground. Its the same trick.

Mark
6  Using Arduino / Project Guidance / Re: Making the needle move on a rev meter on: Today at 07:10:24 am
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The pulses will very in frequency like a PWM signal.

The frequency of a PWM Signal does NOT change, its the duty cycle that is changed.


Mark
7  Using Arduino / Project Guidance / Re: Time Stamping on a NanoSecond Scale on: August 29, 2014, 07:18:54 am
Then look at other tech, er DSP's maybe or FPLA?

Mark
8  Using Arduino / Project Guidance / Re: Different uses for serial communication on: August 27, 2014, 03:26:55 pm
You missed out on SPI which like I2C has hardware support with in the AVR's. Add to that some chips have hardware support for USB built in.

Mark
9  Topics / Robotics / Re: Make:it Robotics Starter Kit problem on: August 27, 2014, 02:40:27 pm
Replace battery, always use rechargeable batteries A PP3 will be flat in 2 mins or so AA 20-30 mins.

Provide a link to what you have.

Mark
10  Using Arduino / Programming Questions / Re: help in relay ! on: August 26, 2014, 05:28:05 pm
Why are you re-posting the same question?

Mark
11  Using Arduino / Project Guidance / Re: Controlling voltage out of Arduino (to replace vactrol) on: August 26, 2014, 05:22:14 pm
You could look at replacing the LDR's with an opto isolator and then PWM'ing the opto isolators input side. Look in the playground to see how to convert PWM to voltage. Needs 1 or 2 resistors and the same number of cap's.

Mark
12  Using Arduino / Project Guidance / Re: Dimming 220v LED lights on: August 26, 2014, 04:51:13 pm
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But isn't the whole point of a relay isolating your Arduino (and the expensive Intel CPU on the motherboard with the USB port plugged to that Arduino, lol) from anything evil that can happen "on the other side" - particularly if the other side is mains power?

No! People just use relays because they are easy to understand!.

Mark
13  Using Arduino / Project Guidance / Re: Interrupts for a servo on: August 26, 2014, 04:38:26 pm
Instead of sweep take a look at the blink without delay example and then change that to work with the servo. Avoid using loops with in your program (at least in the way that sweep does) Remember that you are already in a never ending loop.

Mark
14  Using Arduino / Project Guidance / Re: Dimming 220v LED lights on: August 26, 2014, 04:20:16 pm
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If you want to control anything "big" (i.e. plugged in on mains electricity), Arduino is ok doing that, but you need a relay in between.

The only good relay is one that has been hit repeatedly with a bloody big hammer.  Take a look at the wiki entry for transistors. this is the mast useful bit http://en.wikipedia.org/wiki/Transistor#Transistor_as_a_switch Relays died when Marconi invented the valve more than 100 years ago. (well ok when they invented the transistor in the 1950's.

Mark
15  Using Arduino / Project Guidance / Re: Controlling voltage out of Arduino (to replace vactrol) on: August 26, 2014, 03:54:59 pm
I don't think that R1 and R2 are LEDs given there names R= resistor.  They are Light Dependant Resistors (LDR).

Which make sense of the drawing's title!

Mark
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