I have connected a DC motor (supply 9V) trough the driver SN754410 via Arduino Mega 2560. I use Labview for control of the DC motor via USB. After the starting of the program I measured that between pins 3 and 7 where the motor was connected, there is a signal up to 6V. I suppose that this is a noise but I am not sure. After 6 seconds after the initialization of Arduino this signal desapears. This is a problem because when the motor is connected to Arduino, the program stops working and the communication between Arduino and my PC stops too.
My question is how to eliminate this noise signal of 6V?
May be 6V to input it is a normal signal during the initialization of Arduino at the beginning. But I would like to set a control voltage to the motor when I push a button from the software application. This voltage at the beginning is trying to start the motor. That is the problem.
When the Arduino starts up all the pins revert to inputs by default. This means that they "float". If you want a pin to be at a specific logic level during initialisation then use a 10K pull up or pull down resistor on that pin.
From your diagram I note that your SN754410 has no logic supply decoupling capacitor and your 9V motor supply has not got a common ground with the Arduino.
These need to be addressed either in real life or the diagram or both.
I have corrected my diagram according to your suggestions. I put 2 pull-up resistors to the pins 8 and 9 of Arduino. I have connected the minus of the adapter to the ground of Arduino. I put one resistor (100 microfarads) between the logic supply (5V) and the GND.
Now, have 9V between the pins 3 and 6 of the driver during the initialization of Arduino at the beginning. There is an error I think.
The 100uF is not very good at combating high frequencyes, to need to add another capacitor which is 0.1uF and of the ceramic type, this will stabilise things.
If not then you need to post the code you are using and also a photograph showing of your wiring so we can check it is right.
I have connected a capacitor 0.1uF of ceramic type but the signal is still not good between the pins for control of the DC motor. I am sending my diagram for corrections.
You have not got the hang of this forum have you. You gave me a photograph of a solderless bread board with components loosely scattered over it.
The only thing I can tell from that is that the 0.1uF capacitor is no where near the chip. It has to be as close to the chip's pins as possible to do any good.
Sigh.
The code in the freeking Arduino is what I was expecting. This is the first mention of LabView it changes everything I have said about the software so far.
Very cross with you, you are a time waster.
In reply #1 I asked for your code and we have to get down to #13 before you tell me this!
So what the chuf is in the Arduino? Is it Firmatra?
