Problem with common ground, trying to control 2 DC motors with L298N

Hi,

i'm an intermediate programmer, long-time electronics novice.

I've followed multiple tutorials on Youtube on how to hook up an L298N h-bridge with an Uno to drive 2 DC motors, but so far i can't get a single motor to work, PWM or no PWM, even though the process is straightforward and uncomplicated.

The trouble seems to be that when i attach the Uno ground to the ground of the h-bridge, the current from the bench PSU i'm using to power the h-bridge goes high very quickly as voltage is raised, so i can't raise to the the 5V needed to power the h-bridge without worrying about smoking something.

This happens whether i power the Uno from USB or wall adapter, i've tried the ground pin next to AREF and the ground pin in the POWER row since i've seen it done both ways in various videos.

This is an example of the videos i've watched, the wiring is simple and the process seems easy so i'm not sure what i'm doing wrong :

Thanks for any help.

Been reading a few posts here about the L298N, hadn't realised it was a bit of a dinosaur, would this be a good replacement :

Thanks.

I have a few of the Pololu version of those drivers and I'm very pleased with them. Be aware that their voltage range is 2.7 to 10.8V and the max RMS current for one driver is 1.5 amps. I use mine with a 1S LiPo battery (3.8v).

The Pololu website has a good range of DC motor drivers to give you some idea of what is available. Similar products are available from other suppliers.

If you need more current and voltage and don't mind doing some soldering the Infineon TLE5206 can control 5 amps and has over-current protection.

...R

Robin2:
I have a few of the Pololu version of those drivers and I'm very pleased with them. Be aware that their voltage range is 2.7 to 10.8V and the max RMS current for one driver is 1.5 amps. I use mine with a 1S LiPo battery (3.8v).

The Pololu website has a good range of DC motor drivers to give you some idea of what is available. Similar products are available from other suppliers.

If you need more current and voltage and don't mind doing some soldering the Infineon TLE5206 can control 5 amps and has over-current protection.

...R

Thanks Robin2.

Does anyone know why i get too much current as soon as i attach the Uno to common ground?

Using the adapter rather than USB for power input to the Uno it now works, but in the YT video his Uno is on USB so i still haven't learned anything here, unless it's to do with USB isolation ?

commonground:
Does anyone know why i get too much current as soon as i attach the Uno to common ground?

It’s not clear from your opening post if you have a standalone L298 chip, or one of the many modules using the chip but providing ancilliary electronics and connections. You might provide a schematic here; maybe more than one, showing the various power configurations you’ve tried.

But your idea to modernise is a good one; you will always lose almost 2V through the L298, closer to 5V with higher current, so now’s your chance to get something more efficient. From the datasheet:

298 volt drop.GIF

commonground:
Does anyone know why i get too much current as soon as i attach the Uno to common ground?

I don't know what you mean by that. Please post a wiring diagram. See this Simple Image Guide

...R

Robin2:
I don't know what you mean by that. Please post a wiring diagram. See this Simple Image Guide

...R

Blimey, not the simplest image-upload method i've come across on a forum!

I was using a dual L298N module, the one in the linked image and using the same wiring :

Thanks.

commonground:
Thanks Robin2.

Does anyone know why i get too much current as soon as i attach the Uno to common ground?

Have you measured the voltage between the two grounds when they are not connected with
a multimeter (both AC and DC volts)? Then do the same with a 1k resistor between them.

The L298 module that I have is different. All my screw terminals are on one edge of the PCB and the logic connections are on the opposite edge. I have always connected the GND to the motor power supply and to my Arduino. There is only one GND connection on my module.

...R

Thanks MarkT and Robin2, i'll measure the voltages later Mark.

Thanks.