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1  Using Arduino / Motors, Mechanics, and Power / Re: Micro Metal gear motor with shaft encoder on: Today at 05:29:40 am
Study the BlinkWithoutDelay example...  Rather than stopping and waiting
you regularly check.
2  Using Arduino / Motors, Mechanics, and Power / Re: Does this MOSFET implementation look correct? on: July 25, 2014, 07:24:24 am
The problem with low-side switching is that grounds are no longer common,
which can have various issues...  Or it might be OK.

Either way you also have to be aware of accidental powering via signal
lines in CMOS, which is why its great to have a shutdown pin on a chip
so you can put it in low power quiescent mode without having to worry about
such things.
3  Using Arduino / Motors, Mechanics, and Power / Re: L293D no power on output on: July 24, 2014, 06:36:06 pm
PP3-sized 9V batteries are not designed to power motors at all and may struggle
to do anything.

What voltage is the motor?  What is its stall current?  Do you realise that if
the motor pulls enough current to crowbar the output voltage of the 9V
battery it will pull current from the Arduino instead, probably resetting it.

Something like 4 to 6 quality NiMH rechargable AA cells are a good supply for
small 6V motors.
4  Using Arduino / Motors, Mechanics, and Power / Re: How to Control a Motor that has Been Taken Out of a RC Car with the Arduino on: July 24, 2014, 06:26:34 pm
You will also see the Vsat of the drivers at that current level and realise the chip will
be dissipating 15W or so at that current which is only possible on the version
with a tab if mounted on a large heatsink with a fan or with liquid cooling.

Absolute maximum ratings are not recommended operating conditions, and never have been.
5  Using Arduino / Motors, Mechanics, and Power / Re: Troubleshooting a L293D Circuit on: July 24, 2014, 06:21:59 pm
You perhaps fried it?  Have you connected all the ground pins and added decoupling on
both supplies near the chip?
6  Using Arduino / Motors, Mechanics, and Power / Re: Controlling DC Motors with direct PWM signals? on: July 24, 2014, 06:17:16 pm
Also which motors are you thinking of?  You need to match the motor driver and
supply to the motor, and realise you power it separately from the Arduino.
7  Using Arduino / Motors, Mechanics, and Power / Re: How to Control a Motor that has Been Taken Out of a RC Car with the Arduino on: July 24, 2014, 06:13:29 pm
But first you need to find out how much current the motor takes - motor
drivers like the L293 and L298 have very limited current capability.

Some more information about the car and or motor?  Measure the motor
resistance?
For example, i use a L298N, which can handle a total of up to 4A.. In my opinion this is not a "very limited current capability" ...
Sure it's a good idea  to find out how much current the motor takes, just in case !!!!
Ha, good joke...    No, the L298 will not handle 4A.  Assume each channel will manage 1A
at most and get super-hot doing that.  Sure it can handle 2A peak per channel but without
liquid cooling forget trying to run that continuously, its a darlington-based chip.
8  Using Arduino / Motors, Mechanics, and Power / Re: Does this MOSFET implementation look correct? on: July 24, 2014, 06:10:33 pm
Sorry, I've attached a larger version to the first post which should be better.

Now I can see the diagram you seem confused.

At the bottom left there is a p-channel MOSFETsymbol  labelled "NTR4501N" which is
an n-channel MOSFET.  You also draw the drain to Vcc and source to the load
which is wrong.

You need p-channel device with source to Vcc, drain to the load, to do high-side switching.

A simple hand-drawn sketch would have sorted this all out in the first instance...

This is high-side p-chan switch:


Note the diode is part of the device in all power MOSFETs, and note the direction of the
arrow on the channel which indicates its a p-channel device.
9  Using Arduino / Motors, Mechanics, and Power / Re: Servo motor helppppp on: July 24, 2014, 05:51:21 pm
Sounds like way too much torque for any normal hobby servo.  You need to redesign
your mechanics to be balanced.
10  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.
11  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
12  Using Arduino / Programming Questions / Re: problem with serial communication on: July 24, 2014, 05:30:54 pm
Code:

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
13  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
buffers.

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.
14  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.
15  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!
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