> 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-fnd-eval.md).

# LAB: GPIO 7-segment(eval board)

## LAB: GPIO 7-segment(eval board)

### LAB: GPIO 7-segment

**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 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:
  * eval board

**Software**

* PlatformIO, CMSIS, EC\_HAL library

### Exercise

Fill in the table

| **Port/Pin**    | **Description**              | **Register setting**                      |
| --------------- | ---------------------------- | ----------------------------------------- |
| Port B Pin 5    | Clear Pin5 mode              | GPIOB->MODER &=\~(3<<(5\*2))              |
| Port B Pin 5    | Set Pin5 mode = Output       | GPIOB->MODER \|=\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B Pin 6    | Clear Pin6 mode              | GPIOB->MODER &=\~\_\_\_\_\_\_\_\_\_\_\_   |
| Port B Pin 6    | Set Pin6 mode = Output       | GPIOB->MODER \|=\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B Pin Y    | Clear PinY mode              | GPIOB->MODER &=\~\_\_\_\_\_\_\_\_\_\_\_   |
| Port B Pin Y    | Set PinY mode = Output       | GPIOB->MODER \|=\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B Pin 5\~9 | Clear Pin5\~9 mode           | GPIOB->MODER &=\~\_\_\_\_\_\_\_\_\_\_\_   |
|                 | Set Pin5\~9 mode = Output    | GPIOB->MODER \|=\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port X Pin Y    | Clear Pin Y mode             | GPIOX->MODER &=\~\_\_\_\_\_\_\_\_\_\_\_   |
|                 | Set Pin Y mode = Output      | GPIOX->MODER \|=\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B Pin5     | Set Pin5 otype=push-pull     | GPIOB->OTYPER =\_\_\_\_\_\_\_\_\_\_\_\_   |
| Port B PinY     | Set PinY otype=push-pull     | GPIOB-> OTYPER =\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B Pin5     | Set Pin5 ospeed=Fast         | GPIOB->OSPEEDR =\_\_\_\_\_\_\_\_\_\_\_\_  |
| Port B PinY     | Set PinY ospeed=Fast         | GPIOB-> OSPEEDR =\_\_\_\_\_\_\_\_\_\_\_\_ |
| Port B Pin 5    | Set Pin5 PUPD=no pullup/down | GPIOB->OTYPER =\_\_\_\_\_\_\_\_\_\_\_\_   |
| Port B Pin Y    | Set PinY PUPD=no pullup/down | GPIOB-> OTYPER =\_\_\_\_\_\_\_\_\_\_\_\_  |

***

## Prelab: 7-segment Display

#### Procedure

Complete the Tutorial: **7-segment Display : Option 2. Without a 7-segment decoder**

{% embed url="<https://ykkim.gitbook.io/ec/ec-course/tutorial/tutorial-7segment-display#option-3.-without-using-a-7-segment-decoder-on-jkit-evaluation-board>" %}

You must check the 7-segment display can show all the number from 0 to 9.

* Give all 'HIGH' and 'LOW' signal to pin 'a'\~'g'
* Observe all LEDs are turned ON or OFF
* You must show the result to TA

## Problem 1. Library for 7-segment display on JKIT Board

#### Problem

There are four 7-Segment Displays on JKIT board.

* You need to select which one to use.
* There is no BCD decoder
* JKIT - Nucleo 64: [link](https://www.devicemart.co.kr/goods/view?no=14123215\&srsltid=AfmBOooT3zgaxGXZ_q0fvy4uZxHesTbwpqNprE6P3YXMk9V0EGoGrhLM)

<figure><img src="https://raw.githubusercontent.com/LeeJunjae1/EC_22000573/main/img/connect.jpg" alt="" width="375"><figcaption></figcaption></figure>

Complete the required functions that displays numbers on 7-segment FND.(JKIT - Nucleo 64)

These functions are defined and declared in `ecGPIO2.h,ecGPIO2.c`

```c
// Display a number 0 - 9 only
void FND_display_init(PinName_t *pinFND);
void FND_display(uint8_t  num)

// Select display: FND0 to FND3
void FND_select_init(PinName_t *selectFND);
void FND_select(uint8_t select);
```

Display a decimal number: 0\~9 on each and all FNDs

{% hint style="info" %}
If you want to display multiple 7-segment displays at the same time, you need to use a very short delay to select multiple numbers iteratively
{% endhint %}

{% hint style="info" %}
**Check if the 7-segments display are Common Anode or Cathode**

**For Common Cathode: Giving 'High' to the pin -> LED ON**
{% endhint %}

#### Procedure <a href="#procedure-2" id="procedure-2"></a>

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\_7segment”**
* Source File: ““**LAB\_GPIO\_7segment.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**

<div align="center"><img src="https://raw.githubusercontent.com/LeeJunjae1/EC_22000573/main/img/7seg.png" alt="config" width="188"> <img src="https://raw.githubusercontent.com/LeeJunjae1/EC_22000573/main/img/LED.png" alt="LED Choose" width="375"></div>

| Function                           | Port - Pin                                                                                            | Configuration                 |
| ---------------------------------- | ----------------------------------------------------------------------------------------------------- | ----------------------------- |
| **Selection of 7-Segment Display** | <p>PA\_10, PA\_11, PC\_4, PC\_3<br>(FND\_0\~FND\_3)</p>                                               | DOUT, Push-Pull,              |
| **7-Segment LEDs**                 | <p>PB\_0, PB\_1, PB\_2, PB\_3, PB\_4, PB\_5, PB\_6, PB\_7</p><p>('a'\~'g''dot', respectively)<br></p> | DOUT, Push-Pull, Medium Speed |

**Example Code**

{% tabs %}
{% tab title="main\_sample" %}

<pre class="language-c" data-expandable="true"><code class="lang-c"><strong>#include "stm32f4xx.h"
</strong>#include "ecGPIO2.h"
#include "ecRCC2.h"

PinName_t pinFND[8]    = {PB_0, PB_1, PB_2, PB_3, PB_4, PB_5, PB_6, PB_7};
// PinName_t selectFND[4]={PA_10, ... }
// [YOUR CODE GOES HERE]

void setup(void){
    // Intialize System Clock
    RCC_HSI_init();    
    // Intialize FND pins and Others
    FND_init(pinFND);
    FND_select_init(selectFND);    
    // Intialize  Others
    // [YOUR CODE GOES HERE]    
};

int main(void) {
    setup();
    uint8_t numDisplay1  = 0;
    uint8_t numDisplay2  = 5;
    uint8_t selectFND1  = 0;
    uint8_t selectFND2  = 1;

    while (1) {
        FND_select(selectFND1);
        FND_display(numDisplay1);
        delay_ms_HSI(1);             		
        FND_select(selectFND2);
        FND_display(numDisplay2);
        delay_ms_HSI(1);	
    }
}


</code></pre>

{% endtab %}

{% tab title="GPIO.h" %}
{% code expandable="true" %}

```c
////////////////////////////////////////////////////////////////////
/* Include the following in GPIO.h */
////////////////////////////////////////////////////////////////////

// FND for JKIT board 
extern int numberFND[12][8];
void FND_init(PinName_t *pinFND);
void FND_select_init(PinName_t *selectFND);
void FND_display(uint8_t num);
void FND_select(uint8_t digit);

```

{% endcode %}
{% endtab %}

{% tab title="GPIO.c" %}

```c
////////////////////////////////////////////////////////////////////
/* Include the following in GPIO.c */
////////////////////////////////////////////////////////////////////

// FND - JKIT board
static PinName_t _fndPins[8];
static PinName_t _fndSel[4];

//Each led that has to light up gets a 1, every other led gets a 0
//its in order  { (a,b,c,d,e,f,g,dp) }
int numberFND[12][8]={
    {1,1,1,1,1,1,0,0},		//zero
    {0,1,1,0,0,0,0,0},		//one
    {1,1,0,1,1,0,1,0},		//two

    // [YOUR CODE GOES HERE]
    // [YOUR CODE GOES HERE]
    // [YOUR CODE GOES HERE]
    {0,0,0,0,0,0,0,1}          //dot
   	{0,0,0,0,0,0,0,0}		      //blank
};
                  

// Initialize DOUT pins for 7 segment leds
void FND_init(PinName_t *pinFND){
	for (int i=0; i<8; i++){
		_fndPins[i] = pinFND[i];
		GPIO_init(_fndPins[i], OUTPUT);
	}
}

// Initialize select pins (FND0~FND3) as DOUT
void FND_select_init(PinName_t *selectFND){	
    // [YOUR CODE GOES HERE]
    // [YOUR CODE GOES HERE]
}

// Display a number 0 - 9 only
void FND_display(uint8_t num){
    // [YOUR CODE GOES HERE]    
    // [YOUR CODE GOES HERE]        
}

// Select display: FND0 to FND3
void FND_select(uint8_t digit){
    // [YOUR CODE GOES HERE]    
    // [YOUR CODE GOES HERE]        
}

////////////////////////////////////////////////////////////////////





```

{% endtab %}
{% endtabs %}

## Problem 2: Counter with Button Press <a href="#problem-1-display-a-number-with-button-press" id="problem-1-display-a-number-with-button-press"></a>

#### Procedure <a href="#procedure-1" id="procedure-1"></a>

\
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.
* Modify from Problem 1 source code

#### Configuration

Configure the MCU GPIO

| Function                           | Port - Pin                                                                                        | Configuration                                 |
| ---------------------------------- | ------------------------------------------------------------------------------------------------- | --------------------------------------------- |
| **Button (SW2) on JKIT**           | PA\_4                                                                                             | DIN, Pull-Up                                  |
| **7-Segment DOUT**                 | <p>PB\_0, PB\_1, PB\_2, PB\_3, PB\_4, PB\_5, PB\_6, PB\_7</p><p>('a'\~'g''dot', respectively)</p> | Push-Pull, No Pull-up-Pull-down, Medium Speed |
| **Selection of 7-Segment Display** | PA\_10 (FND\_0)                                                                                   | DOUT, Push-Pull,                              |

**\* Challenge : Extend the display number from 0 to 19**

**Code**

[**Sample Code**](https://ykkim.gitbook.io/ec/stm32-m4-programming/example-code#seven-segment).

Your code goes here:

> Explain your source code with necessary comments.

```
// YOUR MAIN CODE ONLY
// YOUR CODE
```

#### Connection Diagram

Circuit diagram (if needed)

> You need to include the circuit diagram

![image](https://user-images.githubusercontent.com/38373000/192134563-72f68b29-4127-42ac-b064-2eda95a9a52a.png)

#### 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. Analyze the result and explain any other necessary discussion.
2. What are the common cathode and common anode of 7-segment display?

> Answer discussion questions

3. 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

4. How can we display 4 digit-numbers on the 4 FNDS at the same time? How to remove ghosting of displaying a number?

> Answer discussion questions

***

### Reference

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

```
```

***

### Troubleshooting

(Option) You can write Troubleshooting section