> For the complete documentation index, see [llms.txt](https://ykkim.gitbook.io/EC/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ykkim.gitbook.io/EC/ec-course/lab/lab-gpio-digital-inout-eval.md).
# LAB: GPIO Digital InOut(eval board)
## LAB: GPIO Digital InOut
**Date:** 2026-09-02
**Author/Partner:** YOUR NAME GOES HERE
**Demo Video:** Youtube link
**PDF version:**
## Introduction
In this lab, you are required to create a simple program that toggles multiple LEDs using a push-button input.
You must create your own drivers for GPIO digital input and output control.
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.
```cpp
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](https://github.com/ykkimhgu/EC-student/tree/main/stm32duino-tutorial).
```cpp
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
#### **Prepare Library Files**
Manage your library in the directory of `\repos\EC\include\`.
> 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.](/EC/ec-course/tutorial/tutorial-platformio-in-vscode.md)
* **For uVision User:** Save your header library files in this directory. [See here for detail.](https://ykkim.gitbook.io/ec/uvision/adding-my-api-header-in-uvision)
[Download library files.](https://github.com/ykkimhgu/EC-student/tree/main/include/lib-student)
* `ecRCC2.h, ecRCC2.c`
* `ecPinNames.h, ecPinNames.c`
* `ecGPIO2_student.h, ecGPIO2_student.c`
Create your own library for GPIO by renaming the downloaded files (`ecGPIO2_student.*)` as
* `ecGPIO2.c`, `ecGPIO2.h`
* Open `ecGPIO2.c` and change from `#include "ecGPIO2_student.h"` to `#include "ecGPIO2.h"`
* Write your name and modified date in the comment section
> You MUST write your name inside the comment section.
#### Function Definitions
Fill-in the blanks in the header files to complete the definitions for the provided functions
**ecGPIO2.h**
```cpp
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);
```
* Example code in **ecGPIO2.c**
```cpp
// 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);
}
```
***
## Problem 2: Toggle a single LED with Digital Sensor(Photodetector)
### Problem
Toggle the LED by covering the photodetector sensor.
* Dark (LED ON), Bright (LED OFF) and repeat
* Connect the Photodetector sensor to PA\_0 pin on Nucleo Board.
### Procedure
1. Connect the evaluation board [(JKIT-NUCLEO) ](https://ykkim.gitbook.io/ec/ec-course/hardware/stm32f-evaluation-board#reference-manual)to the MCU.
2. Make sure that your library **ecGPIO2.h, ecGPIO2.c** are in `EC\include\`.
3. Create a new project under the directory `EC\lab\`
* Environment: “**LAB\_GPIO\_DIO\_LED\_Photosensor”.**
* Source File: “**LAB\_GPIO\_DIO\_LED\_Photosensor.c”**
4. You must modify the **`platformio.ini` ,** to add new environment.
### Configuration
Configure the MCU GPIO
| Function | Port - Pin | Configuration |
| ------------------------- | ---------- | ----------------------------------------------------------- |
| **Photodetector on JKIT** | PA\_0 | Digital IN, Pull-Up |
| **LED0** | PB\_12 | Digital OUT, Pull-UP,
Open-Drain, Medium Speed
|
### Code
Your code goes here:
Explain your source code with necessary comments.
**Sample Code:** [example code](https://github.com/ykkimhgu/EC-student/blob/main/lab/lab-student/LAB_GPIO_DIO_LED_student.c)
```cpp
/*----------------------------------------------------------------\
@ Embedded Controller by Young-Keun Kim - Handong Global University
Author : [ YOUR NAME GOES HERE !!!!!]
Created : 05-03-2021
Modified : 00-00-2026 [WRITE THE DATE!!!!]
Language/ver : C++ in VS Code
Description : [WRITE BRIEF DESCRIPTION] !!!!!!
/----------------------------------------------------------------*/
#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);
delay_ms_HSI(100); // delay 100 ms
}
}
```
## Problem 3: Toggle multiple LEDs with a button
### Problem
Use the four LEDs (LED0 to LED3) on the JKIT evaluation board.
Each time Button B1 is pressed, turn on one LED at a time in a sequential loop
* e.g., LED0 -> LED1 -> LED2 -> LED3 -> LED0)
### Procedure
1. Connect the evaluation board [(JKIT-NUCLEO) ](https://ykkim.gitbook.io/ec/ec-course/hardware/stm32f-evaluation-board#reference-manual)to the MCU.
2. Make sure that your library **ecGPIO2.h, ecGPIO2.c** are in `EC\include\`.
3. Create a new project under the directory `EC\lab\`
* Environment: “**LAB\_GPIO\_DIO\_multiLED”**
* Source File: ““**LAB\_GPIO\_DIO\_multiLED.c”**
4. You must modify the **`platformio.ini` ,** to add new environment.
> You MUST write your name in the top of the source file, inside the comment section.
### Configuration
| Function | Port - Pin | Configuration |
| ------------------ | ------------------------------ | ----------------------------------------------------------- |
| **SW2 on JKIT** | PA\_4 | Digital IN, Pull-Up |
| **LED\_0\~LED\_3** | PB\_12, PB\_13, PB\_14, PB\_15 | Digital OUT, Pull-UP,
Open-Drain, Medium Speed
|
### Circuit Diagram
Draw Circuit diagram (if necessary). No need to draw circuit diagram when using JKIT.
> 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](https://github.com/ykkimhgu/course-doc/blob/master/course/lab/link/README.md)
### Discussion
1. Find out a typical solution for software debouncing and hardware debouncing.
2. What method of debouncing did this NUCLEO board use for the push-button(B1)?
> Answer discussion questions
## Reference
Complete list of all references used (github, blog, paper, etc)
```
```
## Troubleshooting
(Option) You can write a Troubleshooting section