LAB: GPIO Digital InOut 7-segment

Date: 2024-09-1

Author/Partner:

Github: repository link

Demo Video: Youtube link

PDF version:

Introduction

In this lab, you are required to create a simple program to control a 7-segment display to show a decimal number (0~9) that increases by pressing a push-button.

You must submit

LAB Report (*.pdf)
Zip source files(LAB***.c, ecRCC2.h, ecGPIO2.h etc...).
- Only the source files. Do not submit project files

Requirement

Hardware

MCU
- NUCLEO-F411RE
Actuator/Sensor/Others:
- 7-segment display(5101ASR)
- Array resistor (330 ohm)
- decoder chip(74LS47)
- breadboard

Software

Keil uVision, CMSIS, EC_HAL library

Exercise

Fill in the table

Problem 0: Connection of 7-Segment Display and Decoder

Procedure

Review 7-segment Decoder and Display from Digital Logic lecture.

Read here: 7-segment tutorial
Read here: How to connect 7-segment decoder to MCU

1. 7-segment display connection

First, connect the common anode 7-segment display with the given array resistors.

Then, apply VCC and GND to the 7-segment display.

Check that all LEDs of 7-segment work properly

Give 'H' signal to each 7-segment pin of 'a'~'g' . Observe if that LED is turned ON or OFF
Example: Connect VCC to all 'a'~'g' pins

2. BCD 7-segment decoder connection

The popular BCD 7-segment decoder chip is 74LS47. With the BCD chip, you need only 4 DOUT pins of MCU to display from 0 to 9.

Connect the decoder chip (74LS47) on the bread board.

Then, Check that the decoder chip works properly

Supply a combination of VCC/GND to the pins of 'A'~'D' of the decoder.
Check if the 7-segment LED display shows the correct number

Connection Diagram

Circuit diagram

You need to include the circuit diagram in the report

Discussion

Draw the truth table for the BCD 7-segment decoder with the 4-bit input.

Answer discussion questions

** YOUR Truth-table  goes here**

What are the common cathode and common anode of 7-segment display?

Answer discussion questions

Does the LED of a 7-segment display (common anode) pin turn ON when 'HIGH' is given to the LED pin from the MCU?

Answer discussion questions

Problem 1: Display a Number with Button Press

Procedure

Create a new project under the directory \repos\EC\LAB\LAB_GPIO_7segment

The project name is “LAB_GPIO_7segment”.
Create a new source file named as “LAB_GPIO_7segment.c”
Refer to the sample code
You MUST write your name on the source file inside the comment section.

Include your updated library in \repos\EC\lib\ to your project.

ecGPIO.h, ecGPIO.c
ecRCC.h, ecRCC.c

Declare and Define the following functions in your library

void sevensegment_display_init(PinNames_t pinNameA, PinNames_t pinNameB, PinNames_t pinNameC, PinNames_t pinNameD); 
void sevensegment_display(uint8_t  num);

num: 0 to 9 only (unsigned)

Configure and connect the MCU to the circuit
First, check that every number, 0 to 9, can be displayed properly
Then, create a code that increase the displayed number from 0 to 9 with each button press.
- After the number '9', it should start from '0' again.

Configuration

Configure the MCU

Digital In for Button (B1)

Digital Out for 7-Segment

Code

Sample Code.

#include "stm32f4xx.h"
#include "ecGPIO2.h"
#include "ecRCC2.h"

#define LED_PIN PA_5
#define BUTTON_PIN PC_13

void setup(void);
	
int main(void) { 
	// Initialiization --------------------------------------------------------
	setup();
	unsigned int cnt = 0;
	
	// Inifinite Loop ----------------------------------------------------------
	while(1){
		sevensegment_display(cnt % 10);
		if(GPIO_read(BUTTON_PIN) == 0) cnt++; 
        if (cnt > 9) cnt = 0;
		for(int i = 0; i < 500000;i++){}  // delay_ms(500);
	}
}


// Initialiization 
void setup(void)
{
	RCC_HSI_init();	
	GPIO_init(BUTTON_PIN, INPUT);  // calls RCC_GPIOC_enable()
	sevensegment_display_init(PA_7, PB_6, PC_7, PA_9);  // Decoder input A,B,C,D
}

Your code goes here: ADD Code LINK such as github

Explain your source code with necessary comments.

// YOUR MAIN CODE ONLY
// YOUR CODE

Results

Experiment images and results

Show experiment images /results

Add demo video link

Discussion

Analyze the result and explain any other necessary discussion.

Problem 2: Program BCD-7-segment decoder

Instead of using the decoder chip, we are going to make the 7-segment decoder with the MCU programming.

Do not use the 7-segment decoder for this problem

Procedure

Use the same project and source file.
Include your updated library in \repos\EC\lib\ to your project.

ecGPIO.h, ecGPIO.c
ecRCC.h, ecRCC.c

Declare and Define the following functions in your library

void sevensegment_decoder_init(void); 
void sevensegment_decoder(uint8_t  num);

num: 0 to 9 only (unsigned)

Configure and connect the MCU to the circuit
First, check that every number, 0 to 9, can be displayed properly
Then, create a code that increases the displayed number from 0 to 9 with each button press.
- After the number '9', it should start from '0' again.