Final answer:
A driver circuit is used instead of connecting a motor directly to a microcontroller pin to prevent damage from high current draw, to ensure the motor receives sufficient current for operation, and to manage varying loads and speeds safely.
Step-by-step explanation:
The use of a driver circuit instead of directly connecting a motor to the pin of a microcontroller is important for several reasons. Microcontroller pins often cannot supply sufficient current to drive a motor and might get damaged due to the high current drawn by the motor when it starts or is under heavy mechanical load. The driver circuit acts as an interface, providing adequate current for the motor to function properly without jeopardizing the microcontroller.
When a motor operates, especially under conditions like climbing a hill with an electric wheelchair, the back electromotive force (emf) drops, and the motor requires more current to do more work. Without a driver circuit, the increased current could cause overheating and potentially burn out the motor. A driver circuit thus helps manage the current flow to the motor, allowing it to run safely at different loads and speeds.