The original problem in the software was that i was writing wrong the code. As I posted the final code is in that thread. From my point of view the software works fine.
I am trying to make a tank controlled by and arduino 2009 with a motor shield like in the link i posted.
My problem is that i have 2 motors that i stripped from a toy that was powered by 4 x 1.5V battery pack.
Now the arduino board is outputting 3,6V on the 4 pins that i use to connect the 2 motors.
Like i said before i tried powering with an external power supply of 5v@1,5Ah (AC to DC converter from a router), 6v@1Ah (4 x 1.5V battery pack like original power supply), and 9v(plain battery), but the output from the shield remains the same.
P.S.: I am using PWM and this happens at the value of 255.
My question is how can i modify the output voltage on those 4 pins that i use for the 2 motors. The target voltage is 6v.
I am mainly interested in how to do this software not hardware.
Sorry software doesn't cut it here.
That link does not show a schematic so it is not too useful.
However if it is based on the L293 you need to connect pin 8 of that chip to the motor voltage. This is a different voltage than the logic supply voltage on pin 16 of this chip. So if the motor shield is designed correctly there should be a separate input for the motor voltage and the logic voltage. The motor voltage you supply should be the one you want the motors to use. If you have not got that voltage available then you need to regulate it from a higher voltage.
From what i have read about this shield it gives @ the output the input voltage from the arduino board. But since this was tested and the output remains at 3.6V i'm starting to wonder.
That's a bad shield design, there are no diodes across the motor outputs. Also as you say the output voltage is limited to the Vcc across the 74HC logic.
As you are only seeing 3v3 output is this with the motors on or not? If it is with the motors on it could be that they are dragging the supply down. If you are measuring it with a voltmeter and are using PWM then the reading you get is meaningless (unless it is PWM at 255 - on all the time)
I measured it without the motors connected and the pwm at 255.
The result was 3.6V. The motors don't drag down the voltage, even when connected.
From my observations when switching from one to another of the 3 power supplies that i mentioned, the speed of the tank varied probably due to the difference of power. This means that the output is influenced by the input power supply, but i can't seem to change the voltage.
This means that the output is influenced by the input power supply, but i can't seem to change the voltage.
That doesn't add up, if the motor speed changes the voltage across it must have changed.
probably due to the difference of power.
Power is voltage times current, you can't change the current without changing the voltage.
So just to recap
Where exactly are you connecting the external voltage to? (the shield or the arduino and what connection)
It is a 5V arduino?
Without the motor but with a load like a resistor (say 1K) you measure either 0V or 3.6V depending on what the program is doing to the input pins. This is measured between one motor output and ground.
Power is voltage times current, you can't change the current without changing the voltage.
Correct. But when you are powering the arduino board through the USB cable you are getting 5V@ a couple of 100mA (300 or 400 if i remember correctly). I connected to the arduino board an AC to DC converter from a router which gives 5V@1500mA. The converter was connected to the power port highlighted with red.
arduino board --- red circle.
i don't understand the question. It is a duemilanove arduino + motor shield v3 (like in picture).
i cannot do this test right now because am @work. but i will do it as soon as i get hime.
The 4 pins highlighted with purple are the outputs for the 2 motors.
I connected to the arduino board an AC to DC converter from a router which gives 5V@1500mA.
I don't care if the power supply is capable of supplying 1500 Amps it will not supply any more power to your motors because the voltage is still only 5V (after regulation). As long as your supply is capable of supplying the current you are drawing from it there is no difference.
So if you are putting the power through the DC input of the arduino you will only ever get 5V output no matter what power supply you use. The exception is when you use a power supply that has too little current capability and the voltage droops as a result.
So to sum up you want 6V output - you can't do it with this hardware without modifying it.
You only get 3.6V output - you defiantly should be getting 5v
BINGO
You are feeding 5V into the DC input jack, this needs at least 7V to work the regulator, that's why you are getting only 3.6V output, the arduino supply is only getting a smaller voltage (3.6V). You need to connect the external PSU output to the +5V line or connect a larger voltage to the input jack.
Yes it was the cheapest i could find, it was for test purposes. Could be a problem? Should i try with another power supply, more pure and stable?
No the one labelled +5V on the arduino board. (it might be the same pin but the photo doesn't show it)
It is the same. So you are saying that if i will connect, let's say a 6V battery pack (4x1.5V) to this pin and GND i will have at the output of the 4 pins a 6V voltage or i will have to have a larger power supply >7V
Could be a problem? Should i try with another power supply, more pure and stable?
Yes it could. I would try.
So you are saying that if i will connect, let's say a 6V battery pack (4x1.5V) to this pin and GND i will have at the output of the 4 pins a 6V voltage
You will but you will also fry the Arduino. I was saying that if you had a 5V supply you should connect it here to give you a 5V powering of the arduino and not the 3.6V powering you are getting.
