Problem with DC Motor and L298N driver

[alexsoad]

Hello,

For my project i am using a L298N motor driver to command 2 DC Motors (200 mA, 6-9V).
For beginning, let me post the part of the schematic where the problem occurs:
**broken link removed**

I made a test board , but i cannot make the motors to start. I set IN1 to 5 volts, IN2 to 0 volts, and EN A to 5 volts (always enable). This must rotate the motor in one way. I used a multimeter to measure the voltage from OUT1 to OUT2, and all looks fine: 6-9 volts, depending on what voltage i select. But when i connect the 2 outputs to a motor, nothing happends.
I have connected two wires to the motor, directly from DC Source, and it does starts, so the problem must be from the driver.
The only thing that does not follows the L298N's data sheet is C7 capacitor. I used a 47uF instead of 470uF, but i do not think this is the problem.

Here is the datasheet of the motor driver:
https://www.farnell.com/datasheets/36721.pdf

I am waiting for any advises .

 

[Audioguru]

I mentioned on another website that your "200mA" motor might need 2A to start. Then it gets only 4.1V for a total of a few minutes if your tiny 9V battery is brand new.

Somebody else commented that your sense resistor value is maybe 1000 times too high.

 

[halee awan]

yes,i think Either you should change Sense Resistors according to your load Or ?

 

[alexsoad]

.update to my problem.
I have removed the 1k Resistor, and i connected the sense pin to ground.
New improvments:
I measure the voltage between OUT1 and OUT2, and it is all ok. (6-7V)
I connect the wires to the motor, and for a short period of time (0.2 sec) the motor starts, but after that it stops.
I measure again the voltage between OUT1 and OUT2, and it isn't ok. (0.2V)
I reset the board=> the voltage between OUT1 and OUT2 is again 6-7 V.

So the L298N stops the motor, and i can't figure out why.....

 

[halee awan]

ok good
Just replace the Ln 298 then see .
one thing more before doing this
confirm that how much current is required for motor ,i think 2A at start up as "Audioguru" told you ..
so confirm it that Ln 298 can source it OR allow it to pass or not ok
...
and second one just check your Hardware with lower rating motor mean that required low current ...
this is the best sulotion for saving the time i think
Good luck

 

[alexsoad]

problem solved

the resistance from the sensing pin is clearly too big and this is the main reason for having no power to supply the motors.
i let for one terminal block the sensing resistance connected, and the motor doesn't starts, and for the second terminal block i removed the sensing resistance, and the motor does work. so this is the problem.

the second thing is that the voltage meassured by me is different with the voltage shown on my variable traf. When i select the traf to output 6 volts, on the board i do have 9 volts. I can't explain why.
The problem was that i was selecting the traf at 4,5 volts to have on the board 6-7 volts. This was not enough for the motors.
I raised the voltage from the traf up to 6 volts, and on the board i had 9 volts. The result: motors are working !

thank you very much for help, and i will come back here with other problems as well, because i just started to test practically my project.

 

[alexsoad]

update:
I made some tests and i cannot explain some results, so i need some help again.
At 12 V, both motors are working fine, but if i lower the voltage down to 9 V, sometimes the motors just don't start.
I don't get it... why? At 9 V sometimes the motors start, but other times they start for only 0,2 sec, and then they stop. After some resets and other retries, the motors start, and i cannot explain this.
I do not understand the cause of this malfunction. Maybe the Shottcky diodes do this stop? Or maybe the L298N?

The second problem is with my IR sensors.
I used a IR emitter, a Photo Diode and some resistances and i created my own sensors. This is the circuit
**broken link removed**



When i use a white paper for the reflection i get on the output ~ 0,3V. When i use black paper for the reflection, i get on the output ~0,05V.
The problem is if i will be able to to differentiate these two voltages. If i will use ADC from uc it will be ok?

 

[Audioguru]

There is a very stong echo on the internet.
I answered this post 10 seconds ago (on another website).

 

[halee awan]

if its......... then I think you can easily ,what is the problem you can read these two value very easily ....

it is 0-3V and 0-5v Sure ?