Page 32 - ARM Based Microcontroller Projects Using MBED

18 2. MICROCONTROLLER-BASED PROJECT DEVELOPMENT CYCLE

ELSE IF HEX_NUM ¼ “E” THEN
DEC_NUM ¼ 14
ELSE IF HEX_NUM ¼ “F” THEN
DEC_NUM ¼ 15
ENDIF
END

The required flow chart is shown in Fig. 2.14. Notice that it is much easier to write the PDL
statements than drawing the flow chart shapes and writing text inside them.

EXAMPLE 2.2
It is required to write a program to calculate the sum of integer numbers between 1 and 100. Show
the required algorithm using a PDL and also draw the equivalent flow chart. Assume that the sum
will be stored in variable called SUM.
Solution 2.2
The required PDL is:
BEGIN
SUM ¼ 0
I ¼ 1
DO 100 TIMES
SUM ¼ SUM + I
Increment I
ENDDO
END

The required flow chart is shown in Fig. 2.15.

EXAMPLE 2.3
An LED is connected to a microcontroller output port. Additionally a button is connected to one of
the input ports. It is required to turn ON the LED when the button is pressed, and otherwise to turn
OFF the LED. Show the required algorithm using a PDL and also draw the equivalent flow chart.
Solution 2.3
The required PDL is:
BEGIN
DO FOREVER
IF Button is pressed THEN
Turn ON LED
ELSE
Turn OFF LED
ENDIF
ENDDO
END