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31  Using Arduino / Programming Questions / Re: Is CRC needed for USB Arduino-Computer communication? on: July 24, 2014, 05:49:03 pm
Another easy way to provide increased reliability is to require each command
to be repeated exactly before it is obeyed, or choose long random strings for
each command so one will not readily morph into another.
32  Using Arduino / Programming Questions / Re: Library for ADS1115 by Adafruit on: July 24, 2014, 05:33:54 pm
it tells me Adafruit_ADS1115 does not have a name type (which I know normally it would be an int or char or double etc.)

No, it tells you that Adafruit_ADS1115 does not name a type.

That's usually because you've failed to install the library / restart the Arduino software
33  Using Arduino / Programming Questions / Re: problem with serial communication on: July 24, 2014, 05:30:54 pm

sketch_jul24a.ino: In function ‘void loop()’:
sketch_jul24a:31: error: ‘serial’ was not declared in this scope
sketch_jul24a.ino: In function ‘void check()’:
sketch_jul24a:46: error: ‘inString’ was not declared in this scope
sketch_jul24a.ino: At global scope:
sketch_jul24a:88: error: expected declaration before ‘}’ token
34  Using Arduino / Programming Questions / Re: Help reducing RAM usage on: July 24, 2014, 05:22:14 pm
You are at the mercy of the SD and Ethernet libraries which both need large

Checkout the source of these to see if there comments about reducing the footprint.
There may be other libraries or versions that use a bit less RAM.
35  Using Arduino / Programming Questions / Re: Setting internal 1.1 reference to a single pin only on: July 24, 2014, 05:13:09 pm
You have one ADC - the reference is for the ADC, not the pin, so is the same for all inputs, but you can change it on-the-fly (though read the restrictions carefully, and expect to waste at least 50% of your reads)

In particular after changing the analog reference setting you must force an ADC conversion
and ignore the result, only thereafter will it return meaningful readings.
36  Using Arduino / Programming Questions / Re: Servo motors lose PWM signal, arduino fio stops writing it on: July 24, 2014, 05:10:20 pm
Many many postings here about motors or servos are due to powering these from the
same supply as the Arduino.

Don't do this - not unless you _really_ know what you're doing and have an oscilloscope...

Also if you post your circuit and your code we might see what the problem is, since
you have only told us the symptoms but we don't get to see the patient!
37  Using Arduino / Programming Questions / Re: for () Statement question. on: July 24, 2014, 05:04:00 pm
This sketch im using has this for () statement in the void setup()

void setup()
  for (int z=1; z<7; z++)
   pinMode(z, OUTPUT);

Is only one pin an output at a time or is it looping in the setup and eventually all 6 are outputs after the set up and this is just an better way than pinMode() for all 6 pins used? Just a little confused.

thanks for any help!

Missing semicolon on the randomSeed line.

Its setting each pin to be an output without the space cost of a line of code
for each one - not an uncommon idiom.

Its more portable than using DDRx resisters.

It would be even more portable to name the pins rather than using hard-coded
numbers - #define or whatever, and to also add a comment alongside the
#defines saying they are assumed to be contiguously numbered.
38  Using Arduino / Motors, Mechanics, and Power / Re: easy drivers vs pololu carriers A4988's vs DRV8825's on: July 24, 2014, 04:49:53 pm
IMO microstepping is better, but x8 or x16 is enough - it reduces resonance,
resonance is the commonest cause of mis-stepping.  Resonance is less of a problem
in belt drives compared to leadscrew drives though, since the belt acts as mechanical
39  Using Arduino / General Electronics / Re: ADC false readings on: July 24, 2014, 04:40:55 pm
I think I've confused this thread with another ADC one, sorry if I've caused others confusion.
40  Using Arduino / General Electronics / Re: What's this peice called? on: July 24, 2014, 04:38:30 pm
It is probably a small resistor.
There speaks someone who's never worked with surface mount components...

Resistors are white with a black film on top with writing printed on them.  Ceramic
caps are brown or sometimes white and never have writing on them.
41  Using Arduino / General Electronics / Re: Linking audio amp problem. on: July 24, 2014, 04:32:13 pm
Oh yes, the TDA7052's noise performance is definitely inadequate, looking
at the output noise graph - they don't say what bandwidth for that graph's noise
measurements but it's pretty shocking however you look at it.

Another issue is the unknown bandwidth v. gain behaviour - it claims 300kHz
bandwidth at -1dB, but at what gain level?  Bandwidth is likely to fall as
gain increases, so its not clear it can handle 40kHz at max gain (after all it is
an audio amp).

So what are you trying to actually do?
42  Using Arduino / General Electronics / Re: Linking audio amp problem. on: July 24, 2014, 04:21:57 pm
In the old days the best audio opamps were NE5532 and NE5534A, both very low
noise, but needed high supply voltage.

What signal level and impedance is the input?  Its a 40kHz microphone right?  That
may require low-noise design - is it piezo or moving-coil?
43  Using Arduino / General Electronics / Re: PCB schematic on: July 24, 2014, 04:11:04 pm
Resistor R2 shouldn't be there in the first place, it may cause problems
for the low power crystal oscillator.
44  Using Arduino / General Electronics / Re: Component to connect parts in parallel on: July 24, 2014, 04:04:53 pm
Is there a component or device that would take a DC current in from one source and then allow you to split that one input into multiple parallel outputs? Sort of like what you can do with one row of a breadboard but more permanent (I dont suppose you pros use breadboards in your finished product do you?

10mA?  1A? 50A?  Details matter smiley-wink
45  Using Arduino / General Electronics / Re: Switching High Current Loads on: July 24, 2014, 03:57:20 pm
That's the wrong configuration for switching - you must have load between supply and drain, source
terminal to 0V / ground.

Remember the gate has to be 5V above the source voltage to turn the device on, so the
source must be at 0V.  (All assuming n-channel logic-level FET).

PS  You probably want the opto coupler pulling the gate high, not down to
ground, so that the MOSFET is off when the Arduino is powered down...

Given your load circuit is all 12V you don't need logic-level MOSFET,  For 10A a
beefy device is needed, perhaps 5 milliohm or lower, if you want to avoid a large
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