Page 152 - ARM Based Microcontroller Projects Using MBED

138 8. INTERMEDIATE LEVEL PROJECTS

/***********************************************************************

2-DIGIT MULTIPLEXED LED
=======================
In this program a 2-digit 7-Segment LED is connected to PORT C of the
Nucleo-F411RE development board. The program displays the number 25 on
the display.
Author: Dogan Ibrahim
Date : August 2018
File : SevenSegMux2
************************************************************************/
#include "mbed.h"
PortOut Segments(PortC, 0xFF);
int LEDS[] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};

DigitalOut MSDEnable(PC_8);
DigitalOut LSDEnable(PC_9);
#define Enable 1
#define Disable 0
int main()
{
int MSDValue, LSDValue, CNT;
CNT = 25; // Number to be displayed
MSDEnable = Disable; // Disable MSD digit
LSDEnable = Disable; // Disable LSD digit

while(1) // Do forever
{
MSDValue = CNT / 10; // MSD of the number
LSDValue = CNT % 10; // LSD of the number
Segments = LEDS[MSDValue]; // Send to PORT C
MSDEnable = Enable; // Enable MSD digit
wait(0.01); // Wait 10ms

MSDEnable = Disable; // Disable MSD digit
Segments = LEDS[LSDValue]; // Send to PORT C
LSDEnable = Enable; // Enable LSD digit
wait(0.01); // Wait 10ms
LSDEnable = Disable; // Disable LSD digit
}
}

FIG. 8.5 Program listing.

8.2.6 Program Listing

The program listing (program: SevenSegMux2) is shown in Fig. 8.5. At the beginning of
the program, PORT C lower byte bits are grouped together and assigned to variable called
Segments using the PortOut statement. PC_8 and PC_9 bits are defined as MSDEnable
and LSDEnable and are configured as digital outputs. At the beginning of the main program,