Page 277 - ARM Based Microcontroller Projects Using MBED

9.2 PROJECT 1—SIMPLE BRUSHED DC MOTOR CONTROL 263

FIG. 9.3 Program PDL.

FIG. 9.4 Program listing.

OFF are defined as 1 and 0, respectively. The program runs in an endless loop formed using a
while statement. Inside this loop the motor is activated for 10s, then stopped for 5s, and then
again activated for 10s. This process continues until stopped manually by the user.

9.2.7 Using a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)
A MOSFET transistor can be used for motors requiring larger currents instead of a bipolar
transistor. Fig. 9.5 shows the circuit diagram with an IRL540-type MOSFET transistor. This
MOSFET has logic level gate drive and is therefore compatible with microcontroller output
circuits. It is also possible to use a relay instead of transistor for even larger voltages and cur-
rents. This is shown in Fig. 9.6.