L298N Motor Driver Circuit Problem

Community General Discussions
, ,
1

L298N-Motor_Driver.pdf (194939Bytes)

Dear LMR,

For some reason I am really struggling with implementing a simple L298N motor driver. I have a simple breadboard robot and I am trying to run a Timya dual gearbox off the driver. I made a recommended circuit from the data-sheet but for some reason when I pull one of the inputs high (by connecting it to 5V power rail) the motor driver does not activate the motor outputs. I used an oscilloscope to measure all the voltages and everything is as it should be but for some reason the outputs always remain grounded. I could appreciate some help as I do not know what I am doing wrong. I have read forums related to this on LMR and have not found a solution. Bellow are pictures of the connections and the circuit. I have also attached the data sheet.

Thanks,
Gonzik

PS I have tried changing the L298N driver and I get the same result so it is not a case of the driver being fried.

SDC12493.jpg


Robot

SDC12492.jpg


Circuit

Bi-directional_DC.png

Recommended Circuit

 

pins_copy.png



My Connections


SOLUTION (synopsis):

My setup worked when I used this schematic: http://www.solarbotics.com/assets/schematics/solarbotics-l298_schematic_complete.jpg

The original setup was wrong because Vss of 5v is needed for logic and Vs for motor power must be at least Vss + 2.5V. I was trying to use 5V for both. From my understanding this difference is necessary to bias the internal transistors of the driver.

Thanks to everyone who helped!


2

Diodes?

Hi Gonzik,

Check the polarity of the diodes. I had the case that the marking on several diodes were wrong.

3

Checked the polarity, all

Checked the polarity, all the diodes seem fine. I tried replacing my diodes (rectifier diodes) with some schottky diodes I had laying around and still no response.

4

Make sure your current sense

You can cross reference the schematic of my Bluetooth RC tank if you like.  Make sure you use two different supplies; Vss of 5v for logic and Vs for motor power that is at least Vss + 2.5V

5

Solarbotics

Solarbotics has a L298n breakoutish board http://www.solarbotics.com/products/k_cmd/

6

More interesting is the

More interesting is the schematic: http://www.solarbotics.com/assets/schematics/solarbotics-l298_schematic_complete.jpg

Gonzik, do you using this schematic?

7

Thanks I got it working. The

Thanks I got it working. The solarbotics schematic is able to handle one input left floating though.

8

Hey Markus thanks for that

Hey Markus thanks for that schematic. I was able to get it working =) I am not sure what was wrong with the one provided in the data sheet. I have one thing I don’t understand though. What is the purpose of the two 47K resistors? Is it to make sure that the enable input is not left floating at any point?

9

Hey thanks actually caring

Hey thanks for actually caring if I got this working :slight_smile: Sorry it took me so long to get back to you guys, I just moved to a new city and it took me a while to set up shop again :wink:

10

just give a try,.,.without

just give a try,.,.without diodes.,., it will smoothly run.,.,

 

11

just give a try,.,.without

just give a try,.,.without diodes.,., it will smoothly run.,.,