Thanks for your replies
I said that motor isn't important beacause we don't need to see it, we just need to know that it's wired the H-bridge.
My 775 motor is a weak one, it draw around 2A at max load, so around 25W. I'm testing it with a 150W power supply, but in the final project, I will use a 12V 3A 36W one.
I know that I'm outputing 3.5V at full PWM because I measure it with a voltmeter, I know that is not a good idea, but I don't have better solution. But whatever the motor is turning very slowly.
I'm controlling the H-bridge with the arduino UNO 5V supply, when you say at least 6V, its for controlling it or the motor power supply ? Do I have to control the H-bridge with at least 6V ?
Tristan