I have a couple medium lego power functions motors
than I want to control speed and direction with the arduino. I am ordering the SN754410NE
to control them. The problem is that I am playing around with them, switching them with a PSMN2R0-30PL
. I am just doing one pin at a time right now so only speed, no direction. When I use the mosfet to switch the low side of the motor it works fine. But when I switch the high side it goes much slower.
If I do anything like add a bit of resistance to the high side it stops working. But if I power it with a clean 5v, down from its usual 9, it runs fine. Just slower. Is this normal? How can I make sure this motor will work with that motor driver chip?