LAB: GPIO Digital InOut(eval board)

LAB: GPIO Digital InOut

Date: 2025-09-02

Author/Partner:

Github: repository link

Demo Video: Youtube link

PDF version:

Introduction

In this lab, you are required to create a simple program that toggle multiple LEDs with a push-button input. Create HAL drivers for GPIO digital in and out control and use your library.

You must submit

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

Requirement

Hardware

MCU
- NUCLEO-F411RE
Eval Board
Actuator/Sensor/Others:

Software

PlatformIO, CMSIS, EC_HAL library

Problem 0: STM-Arduino

We are going to create a simple program that turns LED(LD2) on and off by pressing the user button(BT1), using Arduino Syntax

GPIO Digital In/Out

Create a new project under the directory \repos\EC\lab\

The project folder name is “\LAB_GPIO_DIO_LED”.

Configures the specified pin to behave either as an input or an output.

pinMode(pin, mode)

pin: the pin number to set the model of.
mode: INPUT, OUTPUT or INPUT_PULLUP.

Look up for pinMode() function in arduino reference for detail description.

Example code

Open Arduino IDE and Create a new program named as ‘TU_arduino_GPIO_LED_button.ino’.

Write the following source code: source code.

const int btnPin = 3;
const int ledPin = 13;

int btnState = HIGH;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(btnPin, INPUT);
}

void loop() {
  btnState = digitalRead(btnPin);

  if (btnState == HIGH) 
    digitalWrite(ledPin, LOW);
  
  else 
    digitalWrite(ledPin, HIGH);
  
}

The user button pin is PC13, but this pin cannot be used in arduino. So, you should connect PC13 to pinName D3 by using wire.

Click on upload button. Push the reset button(black) and check the performance.

The LED(LD2) should be turned on when the button is pressed.

Problem 1: Create EC_HAL library

Procedure

Library Header Files

Create the library directory \repos\EC\include\.

For uVision User: Save your header library files in this directory. See here for detail.

DO NOT make duplicates of library files under each project folders

For VS.Code User: Save your header library files in this directory. See here for detail.

Download necessary library files: Download library files from here

ecRCC2.h, ecRCC2.c
ecPinNames.h, ecPinNames.c

Create your own library for GPIO Digital_In and Out

First, download: ecGPIO2_student.h, ecGPIO2_student.c
Download library file from here
Then, modify it as ecGPIO2.c, ecGPIO2.h

ecRCC2.h (provided)

void RCC_HSI_init(void);  
void RCC_GPIOA_enable(void);   
void RCC_GPIOB_enable(void); 
void RCC_GPIOC_enable(void);

ecGPIO2_student.h

void GPIO_init(PinName_t pinName, int mode);
void GPIO_write(PinName_t pinName, int Output);
int  GPIO_read(PinName_t pinName);
void GPIO_mode(PinName_t pinName, int mode);
void GPIO_ospeed(PinName_t pinName, int speed);
void GPIO_otype(PinName_t pinName, int type);
void GPIO_pupd(PinName_t pinName, int pupd);

/*
// Version 1
void GPIO_init(GPIO_TypeDef *Port, int pin,  int mode);  
void GPIO_write(GPIO_TypeDef *Port, int pin,  int output);  
int  GPIO_read(GPIO_TypeDef *Port, int pin);  
void GPIO_mode(GPIO_TypeDef* Port, int pin, int mode);  
void GPIO_ospeed(GPIO_TypeDef* Port, int pin,  int speed);  
void GPIO_otype(GPIO_TypeDef* Port, int pin,  int type);  
void GPIO_pupd(GPIO_TypeDef* Port, int pin,  int pupd);
*/

Example code in ecGPIO2_student.c

/* ecGPIO2.c  */

// Input(00), Output(01), AlterFunc(10), Analog(11, reset)
void GPIO_mode(PinName_t pinName, uint32_t mode){
 	GPIO_TypeDef *port;
	unsigned int pin;
	ecPinmap(pinName, &port, &pin);
    
	port->MODER &= ~(3UL<<(2*pin));     
	port->MODER |= mode<<(2*pin);    
}


/*
// Version 1
// Input(00), Output(01), AlterFunc(10), Analog(11)
void GPIO_mode(GPIO_TypeDef *Port, int pin, int mode){
   Port->MODER &= ~(3UL<<(2*pin));     
   Port->MODER |= mode<<(2*pin);    
}
*/

Problem 2: Toggle a single LED with Digital Sensor(Photodetector)

Procedure

Connect the evaluation board to the MCU.
Create a new project under the directory \repos\EC\lab\

The project name is “LAB_GPIO_DIO_LED_Photosensor”.
Name the source file as “LAB_GPIO_DIO_LED_Photosensor.c”
Use the example code provided here.

2. If you have not done, include your library ecGPIO2.h, ecGPIO2.c in \repos\EC\include\.

You MUST write your name in the top of the source file, inside the comment section.

You must modify the platformio.ini , to add new environment. Read here for detail

Tutorial: PlatformIO in VSCode | ECykkim.gitbook.io

4. Toggle the LED by covering the photodetector sensor.

Dark (LED ON), Bright (LED OFF) and repeat

Configuration

Digital Sensor (Photodetector)

LED

Digital In

Digital Out

GPIOA, Pin 0

GPIOB, Pin 12

PULL-UP

Open-Drain, Pull-up, Medium Speed

Code

Your code goes here:

Explain your source code with necessary comments.

Sample Code

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

#define LED_PIN PB_12
#define BUTTON_PIN PA_0

// Initialiization 
void setup(void) {
	RCC_HSI_init();
	// initialize the pushbutton pin as an input:
	GPIO_init(BUTTON_PIN, INPUT);  
	// initialize the LED pin as an output:
	GPIO_init(LED_PIN, OUTPUT);    
}
	
int main(void) { 
 	setup();
	int buttonState=0;
	
	while(1){
		// check if the pushbutton is pressed. Turn LED on/off accordingly:
		buttonState = GPIO_read(BUTTON_PIN);
		if(buttonState)	GPIO_write(LED_PIN, LOW);
		else 		GPIO_write(LED_PIN, HIGH);
	}
}

Discussion

Find out a typical solution for software debouncing and hardware debouncing.
What method of debouncing did this NUCLEO board use for the push-button(B1)?

Problem 3: Toggle a single LED with a Button

Procedure

Create a new project under the directory \repos\EC\lab\

The project name is “LAB_GPIO_DIO_LED_Button”.
Name the source file as “LAB_GPIO_DIO_LED_Button.c”
Use the example code provided here.

2. Include your library ecGPIO2.h, ecGPIO2.c in \repos\EC\include\.

You MUST write your name in the top of the source file, inside the comment section.

3. Toggle the LED by pushing the button.

Push button (LED ON), Push Button (LED OFF) and repeat

Configuration

Button (B1)

LED

Digital In

Digital Out

GPIOA, Pin 4

GPIOB, Pin 12

PULL-UP

Open-Drain, Pull-up, Medium Speed

Code

Your code goes here:

Explain your source code with necessary comments.

Sample Code

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

#define LED_PIN PB_12
#define BUTTON_PIN PA_4

// Initialiization 
void setup(void) {
	RCC_HSI_init();
	// initialize the pushbutton pin as an input:
	GPIO_init(BUTTON_PIN, INPUT);  
	// initialize the LED pin as an output:
	GPIO_init(LED_PIN, OUTPUT);    
}
	
int main(void) { 
 	setup();
	int buttonState=0;
	
	while(1){
		// check if the pushbutton is pressed. Turn LED on/off accordingly:
		buttonState = GPIO_read(BUTTON_PIN);
		if(buttonState)	GPIO_write(LED_PIN, LOW);
		else 		GPIO_write(LED_PIN, HIGH);
	}
}

Discussion

Answer discussion questions

Problem 4: Toggle multiple LEDs with a button

Procedure

Create a new project under the directory \repos\EC\lab\

The project name is “LAB_GPIO_DIO_multiLED”.
Name the source file as “LAB_GPIO_DIO_multiLED.c”

You MUST write your name in the top of the source file, inside the comment section.

Include your rary ecGPIO2.h, ecGPIO2.c in \repos\include\.
Connect 4 LEDs externally with necessary load resistors.

As Button B1 is Pressed, light one LED at a time, in sequence.
Example: LED0--> LED1--> …LED3--> …LED0….

Configuration

Button

LED

Digital In

Digital Out

GPIOA, Pin 4

PB12,PB13,PB14,PB15

PULL-UP

Push-Pull, Pull-up, Medium Speed

Circuit Diagram

Draw Circuit diagram

You need to modify the circuit diagram. Example Image

Code

Your code goes here

Explain your source code with necessary comments.

// YOUR MAIN CODE ONLY

Results

Experiment images and results

Show experiment images /results

Add demo video link

Discussion

Answer discussion questions

Reference

Complete list of all references used (github, blog, paper, etc)

Troubleshooting

(Option) You can write a Troubleshooting section

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