Arduino Uno doesn't control L298N

[tillmario]

Hello,
I have problems controlling a L298N with an Arduino Uno. (+ 12-V motor and power supply)

When I try this, the motor works fine:

When I connect it to an Arduino and set the pin 7 high, it doesn't work, although with a multimeter I made sure, that there is 5V at Pin 7.

const int IN1=7;
const int IN2=8;

void setup() 
{
  pinMode(IN1,OUTPUT);
  pinMode(IN2,OUTPUT);
  digitalWrite(IN1,HIGH);
  digitalWrite(IN2,LOW);

}

void loop() 
{
 
  }

I tried 5 different L298N and two different Arduinos.
Does someone have an advice?
Greetings, Tom

[CrossRoads]

Do you have a common Gnd for all 3 devices?

[tillmario]

CrossRoads:
Do you have a common Gnd for all 3 devices?

The Arduino is powered by my PC, not by the 5V Output of the L298N if that's what you mean.

[CrossRoads]

So do the Arduino, the L298 board, and the 12V supply all have their Gnd's connected? The drawing doesn't show that.

[groundFungus]

Connect grounds.

[tillmario]

groundFungus:
Connect grounds.

Oops, yes I get it know, why that was the problem. Thank you both.