Page 114 - ARM Based Microcontroller Projects Using MBED

100 7. USING THE Mbed WITH SIMPLE PROJECTS

while statement. Inside this loop the value of CNT is sent to PORT C and CNT is then
incremented by 1. This process is repeated after 1s delay until CNT is greater than 255
(i.e., all LEDS are ON) at which point CNT is reset back to 0.

7.9 PROJECT 6—RANDOM FLASHING LEDs

7.9.1 Description
In this project 8 external LEDs are connected to PORT C the Nucleo-F411RE development
board as in the previous project. The LEDs turn ON and OFF randomly so that they look like
Christmas light. 250ms delay is inserted in every output.

7.9.2 Aim

The aim of this project is to show random numbers can be generated in Mbed programs.

7.9.3 Block Diagram
The block diagram of the project is shown in Fig. 7.25, where 8 LEDs are connected to PORT
C pins of the Nucleo-F411RE development board.

7.9.4 Circuit Diagram
The circuit diagram of the project is shown in Fig. 7.26 where the LEDs are connected using
current limiting resistors.

7.9.5 The PDL
Fig. 7.35 shows the PDL of the program.

BEGIN
Group PORT C lower byte
DO FOREVER
Generate a random number between 0 and 255
Send the generated number to PORT C
Wait 250ms
ENDDO
END
FIG. 7.35 PDL of the program.