Page 109 - ARM Based Microcontroller Projects Using MBED

7.7 PROJECT 4—ROTATING LEDs 95

FIG. 7.27 The project constructed on a breadboard.

BEGIN
Configure used PORT A pins as outputs
DO FOREVER
Turn ON LSB LED
Wait 1 second
Turn ON next higher LEDs until MSB LED
ENDDO
END
FIG. 7.28 PDL of the project.

PORT C pins PC_0 to PC_7 as digital outputs. A while statement is used to create an indefinite
loop. Inside this loop a for statement is used to loop 8 times. The loop counter (variable k)is
sent to PORT A to turn LEDs ON and OFF as required. One second delay is used between each
output.

7.7.8 Modified Program

The program given in Fig. 7.29 can be written using the PortOut statement. This statement
groups the bits of the given port. The first parameter of this statement is the port name, while
the second parameter when set to 1 specifies which bits of the port will be used. In the